My post will be nothing but honest and clear :
This drama is one of the worst fiction I've ever came across. Well, at least not the worst, it's already that. The only thing which COULD have kept me interested was the split personality issue... But even that, through the first 10 episodes I saw, failed badly. No need to lie, it's not even the main plot. The real plot is the love triangle, a love triangle as classical as possible, wanting itself to be "original" only through a split personality....which isn't even original actually.... Then the fact the heroine is a psychiatrist (she's NOT a university student anymore).....is one of the biggest laugh of the past years. She fails badly in that role - or she's purely and simply the worst psychiatrist possible, you choose - she's nothing but a generic (oh let's make her scream to make her appear energetic and funny) woman who was entitled as pyschiatrist to, once again, appear original. Now, if you love those classical love triangle, good for you. Go for it, but you shall be warned your ears might die in the process to the random and unnecessary screams our dear psychiatrist-wannabe let out.

The main actor might be good, but his role(s) are poorly written and based on nothing but clichés, which aren't even used that well either. No matter how good an actor is, he can't do much with something bad between his hands. I genuinly feel bad for him.
The plot is filled with holes, contradictions, unlogical moments that anyone with a minimum of brain capacity can perceive ; only self-blindness or the desire to turn off your brain while watching shows can justify how one could not. Not only that, the use of flashbacks is the worst I've ever seen, as though they do not have the slightest idea how to use it. And no need to come and say "buuuuut it's complex" it is not complex, it merely pretends to be, and complexity never stopped any REAL complex fiction to use flashbacks properly.

Talking about Oh Ri On now. A comic-relief having a dark secret is a reason to watch it ? Certainly, if by pure luck in your entire life it is the first time you see it. Everyone has to start one day right ? 

So yeah, best advice is to momentarily kill your brain if you really want to watch this, oh and buy a headphone, even with a killed brain the screams are still a threat. But a surprisingly another use can be made of this : a way to teach future film directors and scenarists (or writers in general) what to AVOID at any cost.

The "hype" of this show is simple : sugar sweet self-blindness of helpless females, so lost in worshipping, so desperate at not wanting to realize the deep shit this is that they are ready to come up with the stupidest lies to comfort themselves this has actually anything good apart the main actor's acting. But do not worry, in a few years you'll realize how brainless you used to be... At least I hope so.
I don't hate it or love it.  I'm watching it now but I'm sure I could drop it and forget about it.  The main girl is pretty annoying.  I like Shin Se Gi's character and there are a few funny moments but that's it really. I rarely understand why dramas become as popular as they do though.  It sort of has a supernatural feel to it, which tells me the writers are trying to say not to take it too seriously.  I just don't think you can expect much from kdramas when they involve serious issues.  I wonder if they even consult with professionals?

I'm watching Heart to Heart, because it's something I relate to, and I like it, but I wonder if I should be offended myself how they don't portray these people's problems the way they actually are.  I'm still not sure if I feel like it's ok to be using peoples' serious problems as some gimicky plot device and not even showing how it really it is.

Anyway, these dramas must be selling since there's so many so kaching$ i guess
I unfortunately agree with both Splitgirls and Intimation. I don't understand why people fall so much into these traps that writers throw where the story pretends to be complex when it actually isn't. Or because it has one fresh element, like in this case, the 7 personalities, then everything else must get disregarded because "oooh it's so cool and so fresh and so complex!". Let's face it, it's just another romantic comedy that pretends to be something serious by adding melodrama elements. But reading what @Intimation said, maybe if it attempted to be "just" a romantic comedy, then it would have been a lot better than all the tragical complot sidestory. And I hear even experts call it "original"? In order to make more kaching$ more than likely. x'DAt the end of the day, my opinion counts for myself and not those of others. 
... said the one who gave a 7 to The Heirs...
Thank you HasegawaYui (and chante ?) for showing the inability to judge by yourself. I guess it eases your everyday life, hu ?
@HasegawaYui:  Whaaat? ... So let's get this straight xD if somebody liked Heirs but didn't like Kill Me,Heal Me then the opinion is invalid?...how does that even work? For an instance, Heirs never pretended to be more than a romantic comedy, the characters were typical yes, but at least, yet again, they didn't pretend that they were nothing beyond a poor girl and a rich guy, a Cinderella syndrome.But I'm sure that doesn't count anyway, it didn't have to be Heirs, it could have been any other "overrated" drama. You just needed one to make your point...
Well... you dont like, its ok to express you opinion. But please, dont make idiots of those people, who like this drama. I love it... an Im definately NOT brainless. That is very immature of you.
Anyway, I agree that the drama is unrealistic and unoriginal in some points, but that happenes in almost every korean drama, so I dont see it as such big problem :D
I agree with BPetra. It may not be some award winning truly original artistic piece of work but I enjoy it. It's fine to share your opinions but I also am not brainless and do not appreciate people belittling others just because their opinions differ. 
I have no difficulties in judging by myself and I would gladly debate on every drama with anyone in a respectful way. 
@Bpetra @KiRa : My sis was only calling "brainless" the people that overhype this show as a "masterpiece", blatantly IGNORING the problem and not those that still enjoy it while being aware of what exactly is wrong with it. So she was not reffering to you specifically. ( In case you're confused, I share this account with my sis :)). If you are able to still watch it and enjoy some elements, be our guest, we can't tell anybody what to like or dislike, of course. It's just frustrating when whereever we go we meet fangirls that praise the hell out of this drama as if it's the best thing they've seen in forever....
@Splitgirls : even if I thought this was a masterpiece its rude to belittle the opinions of others, I know she was not referring to me specifically but writing on forums is a form of communication that can easily be misunderstood (since we have to imagine your tone and context) so all people should be careful of their word choice. :) No hard feelings, like I said I don't mind people sharing their opinions but you should not trivialize the feelings and opinions of others. 
I started the show and lost interest rather fast, but not because I thought it was especially bad. However I agree with the others that you're a bit harsh with the people that like Kill Me, Heal Me. Honestly, there are very few korean dramas I have watched that haven't tried to take themselves seriously at one point -- and although I agree with @NekoKirigakure that liking a show that was generally disliked doesn't discredit an opinion, I also understand @HasegawaYui's point about The Heirs: from what I saw of it (yet again another show I dropped), it was actually quite a pretentious show, starting with the original title (He Who Wears the Crown, Endure Its Weight -- how long can it get???). Its plot was used and overused, but the difference with a show such as Boys Over Flowers, for example, is that it took itself very seriously. Was the California part so necessary? It felt so in your face. And honestly, I feel like if there's one show that is falsely complex, it is The Heirs: I hate boiling a story down to its bare structure because I generally believe it's all in the execution, but in the case of this show, I find it necessary. What was all that angst about? A teenager pouting and sulking to get Daddy to change his mind? Why not do something, sacrifice something to earn father's approval?

Okay enough ranting about The Heirs :p , and back to Kill Me, Heal Me. It's no news korean dramas rarely do pure rom-com, and always add something extra: be it split personalities, cross-dressing, a supernatural being falling for a human, mind-reading, body swapping, genius doctors... the list goes on. Yes, it can be irritating, but when I want romance and that's all, well, I turn to other countries. Yes, it feels like in hallyu, they always arbitrarily add some random little extra element to hide the otherwise cliché plot. But at the same time, I feel like that's just on paper -- boiled down, all love stories are pretty much the same, and yes there are recurring characters (the hard-working candy type, the arrogant CEO, the sensitive and selfless second lead...). So yes, Kill Me, Heal Me, is, essentially, the same story as 99% of korean dramas. But you have to admit once you actually watch a drama, they all feel so different, despite the recurring candy-heroine+chaebol-hero+evil-second-lead+love-triangle setup. It's all in the way the actors bring life to their characters, the unique situations that arise from peculiar circumstances, the general atmosphere... So no, it's not "good for you" if a person enjoys a love triangle plot, because it isn't the love triangle per se the person finds interesting, but the relations between 3 characters that have been brought to life. 

And what huge plot holes are you talking about? Perhaps some situations aren't exactly possible, but this is fiction. One has to allow a small margin of irrationality. So far I haven't detected anything major -- or maybe I don't have the "minimum of brain capacity" to perceive it... Also perhaps some things seem illogical at the moment, but will make sens later. Maybe the writers aren't so stupid. And in what way are the flashbacks so very awkward? I personally hated the America part in the first episode for the same reason as the one in The Heirs, but after that, I can't see how the flashbacks are so badly handled it can be "as though they do not have the slightest idea how to use it"... 

I won't argue more about your opinion of the drama because obviously you're entitled to it, but I do have a problem with the insulting tone of your post, even if it's directed only at people who find it a "masterpiece". One drama that is very often qualified as such is Gaksital -- I thoroughly disliked the show because underneath the apparent "complexity", I found it to be very black and white and overly nationalistic (for personal reasons, any form of nationalism rapidly irritates me). However almost everybody loved it, as well as some people whose opinion I look up to. I consider them to be everything but "brainless". Korean dramas are stuffed with clichés, and yet some can annoy one person more than another. These people whose opinion I always find interesting and that liked Gaksital weren't blinded as I was by certain flaws I couldn't get past, and therefore were capable of enjoying its qualities and be touched by the show. In my case I have different expectations for movies that I judge more intellectually, but essentially I want to be touched by something I devote 16+ hours to, I want to feel like I live with the characters for a while. You can't call "brainless" people that are touched by a drama, be it Kill Me, Heal Me or anything else (yes, even The Heirs :p). 



Haha, this basically a 'you're fave is problematic' kind of thing. I was about to comment but I guess Kim-Park-Hee summed everything up quite nicely. 
@Kim-Park-Le: My issue with @HasegawaYui is that it is NOTHING more than a fallacy. A logic error. Well, it is true a lot of people use them without even realizing the erroneous reasoning they are actually performing. But please, tell me how am I supposed to consider an attempt of fallacy as a desire for debate ? But I give you a cookie for trying to go all fallacy on me with The Heirs as well. After all, why do it alone when you can do it in group right ? But anyway I will now explain my stance on The Heirs, since you and so many others find it SO important that I explain myself, fine. Yes, I partially agree with your mini-review on it, however I can't help but notice the words "falsely complex", which is true because it is not. I never came to understand the people that praised it for its complexity because to me it didn't even try to SEEM complex. What do you even define "complex" to begin with? In the dictionary it stands for "complicated", "so complicated or intricate as to be hard to understand or deal with". "characterized by a very complicated or involved arragements of parts or units". Now, exactly how The Heirs try to look complicated with or even seem something more than what it is? (and here I want to point out that I'm harsher than you since you gave it the benefit of the doubt. I gave it none.) A typical "love triangle" + "rich young teenager problems". The discord between the parents and the teenagers? That it actually tried to "care" about other characters that weren't involved in the love triangle? What made it seem that it was trying to be complex? Also "A teenager pouting and sulking to get Daddy to change his mind? Why not do something, sacrifice something to earn father's approval?". You said it yourself, they are TEENAGERS. Do you expect a teenager to suddenly pull out his sword and act like a kind of tragic hero, fighting against the evil, evil parents because "it's just that easy to do something"? The problems in The Heirs are others. xD That said, I don't remember The Heirs ever trying to hide anything or have any kind of hidden plot or hidden meaning that even remotely is as serious and as complex as the "personality disorder" subject btw.

Also, as it seems necessary to point it out : LIKING a drama is NOT equal of quality ; because I liked a drama does NOT automatically mean its quality is good ; DISLIKING a drama is NOT equal of trash ; because I dislike a drama does NOT automatically mean it has a poor quality. Therefore pointing out dramas I liked is POINTLESS.. One would actually think those are rather obvious facts but it is very obviously not the case and it’s THRILLING. (your comment is dripping of this confusion)

“It's no news korean dramas rarely do pure rom-com, and always add something extra: be it split personalities, cross-dressing, a supernatural being falling for a human, mind-reading, body swapping, genius doctors... the list goes on. Yes, it can be irritating, but when I want romance and that's all, well, I turn to other countries.” What??..I’m afraid I did not understand what point there was supposed to be there. Did I say a romance should be a romance without “extras” the end and that’s why this was bad ? Or maybe is it because I said it was poorly done in this case ? If yes, it’s still two unrelated things.

New obvious thing to point out : A cliché or a classic is NOT bad by itself, it’s how you use it which makes the difference. However, KMHM is an amazing example of how to do things wrong in almost every aspect (so not only the stereotypes). (as for the rest, I invite you to reread the thorough DIFFERENCE between liking/disliking and quality again.)

You have the “minimum brain capacity”, the question here is if you use it while watching something or disconnect it. Which I assume you didn't in this case, considering you saw “no major plot holes”. what if you tried rewatching EACH episode while connecting it now ? You’ll see, it’s not that hard to notice them...Come back here when you did and still think that there aren't.

About the flashbacks, oh I don’t know you could go to a cinema school, to a writing school, the best places certainly, or even use internet the one with every answers (at least a start ; certainly, you can always go and search for “how NOT to use flashbacks”). Because yes, sweetheart, there are WAYS to use tools, you just don’t go “oh, let’s put/use/do one here, it’ll be nice 8D”. I don’t think they are stupid (those who did it…and apart from you no one said that), they simply do not give the slightest CRAP and are counting on having enough people disconnecting their brain while watching it. The irony being if connected more often there would be LESS shit as the public would notice they are taken for idiots. And if you still don't know what I'm refering to, I can give you a simple, short answer. Episode 4 (as the best example but definitely not the only one); more than half of the episode was filled with flashbacks from the last three episodes. I sincerely felt mocked while watching it.

A “masterpiece”…yeah, In case it didn’t hit you yet, go to the liking/quality difference section. They can like it so much they want, it is a disaster on too many levels for being called masterpiece, which does NOT mean they can’t like it but simply that calling it a masterpiece is a huge laugh. Normally, if you got the difference you should see the sense in that sentence, if not well, go reread again, if not…I wonder if logic lessons could potentially be of help at that point... Samewise, because you disliked something has nothing to do with something being qualified as “not masterpiece”, again, I hope that by now this appear logical oh and I invite you to the cliché/classical section again if needed.

New obvious : NEVER let your like/dislike BLIND yourself toward its quality. It’s the BEST way for biases (and certainly explains a lot of things). You should ALWAYS be aware of its good AND bad aspects. Not erase one side so it suits yourself better. (in HMKM however I can only find two…two which don’t save a sinking ship) So is it necessary that I point out I do not call brainless those who like it but those who are blind to its flaws ? Or has it finally become obvious ? Talking about The Heirs again, I never denied and never will any of the flaws that it had from cliche, bad characterizations and plotholes. I personally raged and ranted especially through Kim Tan's reactions and decisions, so I can genuinely claim that he had poor characterization problems. I recognize the flaws, my problem is with those that don't, feeling "touched" or not.