First of all i should say this is the first kdrama i ever watched, so excuse me for not being familiar with many things about korean dramas or being overexcited about it. I consider myself a tv junkie, i follow pretty much all the american dramas, but i felt the need to expand in korean dramas as they seem really different and wonderful.
King of high school was a solid drama, i enjoyed it thoroughly, although it had its flaws.

STORY
The main idea of the story was very nice, but the storytelling was poorly executed. There is a HUGE backstory to everything (which was very nice), the show lets you understand that there is something more to the story apart from the obvious scenario, but it doesn't get explored until later episodes, and when it does get explored it gets halfassed. Obviously the writters didn't care about it that much and they used it just to complete the story and make it more complicated.

The main idea of the show is the love triangle between the 3 main characters. It is pretty nice and the ships change all the time, i was pretty much shipping everyone with everyone at some point. I'd prefer if the storytelling was focusing on the backstory to develop it into a mystery and then use the love triangle to just make everything more complicated. Overall it wasn't bad the way it was made though, it just had great potential that was wasted in my opinion.

ACTING
EXQUISITE. I loved it completely. Seo In Guk does a great job, he is funny when he should be, he is cute all the time, he is powerfull, he is great in every way.

But, Lee Soo Hyuk, was the real surprise for me. Of course his character is the best written one, but he did a great job in it. Its not in many shows i go from completely hating a character to completely loving him. This happenned here. Soo Hyuk made my heart acke with almost every scene he was in after episode 8. He was wonderful, heartbreaking and emotional, loved him.

The only reason i didn't give it a clear 10/10 is because of Lee Hana. I think the actress is trying a bit too hard here. She was great, and i guess she was told to be like that, but sometimes her reactions seemed kinda forced. Apart from that i didn't mind her personality it was refreshing seeing a character like hers.

CHARACTER DEVELOPMENT
This is my biggest problem apart from the whole backstory thing i wrote before. The show has a lot of great characters, and almost all of them get on the side for some unnecessary development on the main couple. Sure their love is #goals, and amazing and pure... ok, but i'd like to have seen the development of other characters as well.

Also they tried to develop a 2nd love triangle but it failed misserably ending up one of the main characters getting extremely neglected when she had so much potential.

OVERALL
Overall, i can't say it was the best drama i've ever seen, but i am happy i did watch it. It was funny for the most part and it was emotional in a way i wasn't expecting. I found myself crying and crying like crazy. I'd recommend it to anyone who'd want a great laugh with a wonderful couple in the middle, great acting and some amazing shocks that will make your jaw drop by the end.

EPISODE VALUE:
Episodes 1-6: Setting the story, mostly comedy. I found the first 6 episodes unnecessary, it was watchable, but i'd shrink them in 3-4 episodes.
Episodes 7-13: Love triangle development. GREAT just great episodes. A lot of feels, the 3 main characters develop nicely and everything comes into place. Sometimes the ways the characters find out about their feelings might feel rushed, but sometimes all you need to understand how you feel is one tiny little thing. I appreciated that thought, although i am not sure if it was done on purpose by the writters or it was just... rushed....
Episodes 14-15: Back story revealing. In my opinion this should have been the main premise of the show. The reveals were SHOCKING, i found myself screaming and crying because life and family problems end up being more emotional than love. The backstory should have been developed more, the way they ended it felt rushed as well. Maybe they didn't believe in it, or couldn't think of a better way to end it. Still it was ok.
Episode 16-17: Sweet episodes, kinda continues the love story, the show could have ended in episode 15, there are some unnecessary plot developments here, but still the show concentrates on 2-3 characters and everyone is neglected.

The end was sweet, apart from the already said problem of the neglected characters, i finished the show feeling complete and happy.