I just finished the series and I truly don't know how to feel about it.
I'm going to start with the positive stuff - the cast, acting and soundtrack are all perfect. I especially applaud the actors, who played Juwon and Dongsik - outstanding performances from the both of them. The soundtrack flows beautifully and is just perfect for this series.
However, the story is quite messy and I questioned a lot of the characters' actions. The show falls flat after episode 8, but gets better again after episode 13. Episodes 9-12 were painfully boring to watch. The plot in general is quite hard to follow and confusing, that's why I'm rating the rewatch value at a 10, because then you can rewatch it and try to piece this confusing story together with the context of the characters' motivations and goals. The plot got predictable at times to the point the plot twists could be seen coming from a mile away. The show also left me with some questions, but the most common word in those questions was why. Why did dongsik say nothing when he realised who killed minjeong? Why do none of the characters trust each other? Why did kihwan not stop when he saw yuyeon on the road?
And most importantly, how did they get yuyeon's body in the wall without dongsik knowing? (not a why question but still).
Although this series was frustrating to watch at times, I will happily return to it to give it another chance.