Let's start simple: the art is fantastic, but the story is not.
The art is one of the best I've seen in comicbooks as a whole--not only manhwa. The anatomy is well done and fluid, the character-design is awesome, the colours are great and the backgrounds are fantastic.
But then we get to the story--it's a mess. The author did not plan it out, and he/she probably did not use an outline. That's how it feels, at least.
The story gets sidetracked so much, and it has alot of redundancies. I don't know what's the end goal, and I don't think the author knows either.
But I want to say, the characters are interesting. They're nothing special but they're pretty interesting. Still, alot of them--even the interesting ones--could be removed and the story would be better, more lean.
Anyway, the art carries the whole thing. If not for the art this would be a 5, probably.