The OST, CONCEPT, AND CAST IS REALLY GREAT. The story is supposed to be great but the execution or the storytelling is so confusing.
You'll need to watch and read some explanation videos or article after watching this series so you can get and understand on whats happening. If you want something new and refreshing, try out this one. Rewatch is a must cuz Its really confusing but enjoyable to watch.
Its not your typical korean series and not everyone will like It. Again, we have different preferences. It's really up to our taste. But for me, I LOVE IT!!!