Story
This drama is very well written and tight. There's appropriate amount of cuteness and enough background on the supporting characters to not be annoying and draggy. The usage of flashbacks are well executed and the ending was wrapped up nicely.

Acting/Cast
When the chemistry of the actors come through to the audience, it shows how great an actors' capabilities are for the audience to be able to see and feel what they are projecting and how they tell a story. I believed the characters' feelings for each other, the pain they experience, joy, annoyance etc. I only watched this because of Kim So Hyun but noticed Jang Dong Yoon instead. Another actor I've added into my "to watch out for" list.