Hands down one of my favorite dramas.  Bae Doona first came on my radar  while watching Sense8 (an amazing show, highly, highly recommend). She definitely didn't disappoint in this role either. The cast is amazing, and Cho  Seungwoo and Bae Doona have an amazing chemistry together.  
Multiple  plot twists, most of them completely unexpected. kept me on the edge of  my seat. Probably one of the dramas I've watched quickest, just because  every episode made me want to watch more.  Wasn't my usual cup of tea,  as I'm very much a romantic comedy, happy-go-lucky, cliché drama kinda person. However, wasn't cliché at all, and was very well written, and acted.