I was told the not to read any of the reviews, but to read the book first. having read only four chapters so far, I don't think I will be able to give away significant spoilers; I can't reveal what I don't know. Nonetheless, I'll be careful here.
It's a police procedural, in an unusual environment. It's meticulously detailed and believable, and that's one of its real strengths. It's also quite strange, in directions not usually explored in science fiction or fantasy, and that is its other strength. So far, at least. I expect more of the author, based on what I've read so far.
I suspect the underlying concept may well be as impossible to describe without spoiling the book as the one in Cryptozoic. So I won't.