The story is very compelling. You find yourself caring about pretty much all the characters' stories because they were all just so real and complex. The screenwriters, director and producers did a fantastic job translating this from book to screen. I think a lot of the changes they made actually enriched the show a great deal. All the actors/actresses were amazing in their roles, especially the main leads. Kudos to all the musicians involved in this too because the OST was beautiful. The costumes were top-notch as well.

Finally the icing on the cake: This show has some of the best martial arts scenes I've seen in a loooong time. The choreographer is a genius. They didn't sacrifice the fighting for special effects or extra drama, which is actually kind of rare now.

My only criticism would be that it was too short, and I wish it were a bit longer! Definitely one with a lot of re-watch value.