In a nut shell: this book is really interesting. It's something different that doesn't include a vampire vs werewolf love triangle or anything of the sort. It's not disappointing either, it's right. Just right.
The characters: the characters are interesting actually, just like the book, they're dynamic and realistic, and each and every one of them brings something to plot.
The plot, that's original. It weakens a little in the middle, and occasionally the writing becomes really academic, which can be a bad thing in YA but for this book, I think it actually works.
Notes: I know I haven't given anything away, but that's on purpose! You'll have to read it to know what I'm talking about...