This show is gorgeously created and is so beautifully filmed, scored and casted. The story is really good and really well crafted. I know some people felt the characters were naive but i think that was the point of them. Jo In Sung's acting feels kiddish but it somehow feels right. While Song Hye Kyo's acting shows the main point of her life. The way she executes Oh Young is brilliant. She makes people feel pity for her but still at the same time feel that she a spoiled brat ( BTW everyone in this drama is a grey character ). The Unravelling of her story and Jo In Sung was executed really well. Even Kimbum and Jung Eunji did a really good job even though there characters were poorly written (for me) they both made you feel bad for them. Their story was the one's that didn't make sense on why Eunji was helping Jo In Sung because she was the only one who hadn't ruined her life after the sisters death. Kim Tae Woo's character Moo Chul was really badly written and you almost feel no sympathy for him till he dies.
The Cons of this drama probably starts from episode 12 when the story finally begins. The drama starts off really slow and then just goes in lightening speed. There is so much childlessness and the really irritating twists that don't make any sense is what sinks the whole drama down. Even then its not all episode 16 that you hate this drama it was like ending the drama on the first episode since honestly it can end in the middle of episode 16 when Jo In Sung gets hurt by Kimbum or either be 18 episodes instead of 16. The last episode makes you feel so dissatisfied that it ruins the whole drama for you. Even though the drama starts out brilliantly grips you into each sequence somehow the end is what ruins it for you. This drama would have been on my Top 10 since there is no crazy mother in law or anything but just because of the end it ruins it for you. However i still would suggest you to watch it because even though the end makes you feel dissatisfied the drama is genuinely really enjoyable to watch and the whole process is really fun.