To be completely honest, I think Ji Seungs acting is enough reason to watch this drama. How he managed to portray his different personalities while making them all believable...his performance was outstanding!
As for Hwang Jeong Ums acting, I did think she was annoying at first. Gladly she kinda grew on me the more I got into the drama and, I don't know, it seemed like she really meant what she said.

As I couldn't get this drama out of my head during the days and to then rush home to watch some more episodes, I think it is pretty solid to say that I really enjoyed it.
The plot was interesting enough to keep me entertained, it was well paced all the way through.