To be frank, this isn't nearly as good as I was expecting.
(Admittedly though, after hearing everyone and their brother exclaim over how amazing this manhwa is, with art better than anything else and a really amazing and original plot, said expectations were pretty high.)
The art is pretty, and the occasional full-color pages are cool, since you don't usually see those, let alone done somewhat well, but I didn't think it was anything worth squealing over. In fact, I sometimes can't tell the genders apart, which is annoying - I assumed Yo-hee was guy until, many chapters down the road, someone referred to her as 'she'. And of course, there's the fact that we have two or three characters who look, well, almost exactly alike.
And the story, while certainly out of the ordinary, was just confusing. Sometimes there are time-skips, memory flashes that seem to occur for no apparent reason, but you're not told this and have to figure it out three chapters down the road when you flash back. And I could handle that, I suppose, if they actually cleared things up or explained something to the reader, but half the time they just make things more muddled.
And, at one point, Soah gets sent back to her world because of some...bet? That if she lost her memory wouldn't remember Habaek's name - and she doesn't remember. Several times. Yet the bet isn't lost, and it isn't explained why. And that's just one instance.
And then there's random side stories, and plot twists that don't make sense, and of course, very little real story progression for about forty-something chapters - I've read up to chapter 93, expecting to eventually get some clarity around the story, but I still have almost no clue what is going on.
The characters aren't too cliche, the art is pretty, and the plot is different, but that's about all I can say for this. But, hey, that's just my opinion - I know a lot of other people read and enjoy this series and they really love the artwork and the complexity of the story. I'd say read about the first five or ten chapters to see whose tastes you agree with.