Ok. I'm not sure how to start to write about this drama but let's see.
18 Episodes of 1 hours and a half each.  Analyzing the first half of the drama, you will find a very interesting dark\funny story with a good cast. The drama has a lot of plot twists and it will keep you interested. The acting is good and has a great cast. I have to say I'm not fan of Go Ah Ra but that's just me. Seung Heon does an amazing job and the other supporting actors do a great job. If you like a drama in which most of the tiime you have no idea what's going on regarding the plot, this is for you, but I have to say I have never seing such a complicated plot, the writers really had fun adding stuff lol. The drama is pretty solid into keep you interested but episode 18 (finale) was very weak  and left many things open and many make absolutely no sense. I'm not sure if I would rewatch it but is worth to try it out if you have not seeing it