I think this is one of my favorite drama ever and I'll definitely watch it again. I liked the story the most, then the acting because the chemistry between all of the actors was awesome not just the two mains, also the little touch of comedy was so funny that I rewinded some of the situations xD.
"SPOILER ALERT".. SO The beginning was very well narrated, there was the omg why she wanted to quit, then slower things started to get clear on her reasons. What I also liked was that for once the plot wasn't about a breakup which is typical when the guy is rich and she's not. I also would like to talk about about how the characters were well produced and presented to us, especially his brother and his parents and how it sort of clarifies his personality and why he only believes in himself. And the best thing was probably the last episode when we got a whole new "what's wrong with secretary Kim" but with a different situation. Finally, I really enjoyed and mostly we got so many romantic moments at the end on how each character got its finally too.