The book introduced an interesting concept of parallel cities; however, the concept was confusing and extremely difficult to visualize.
Except for a strange and imperfectly-implemented sci-fi twist, it's a good noir cop story, with good characters and good narration. The sci-fi part, or maybe it's fantasy, is so subtle at first that it's hard to follow even though, or maybe because, all the characters understand perfectly. The ultimate explanation for the sci-fi part isn't especially believable, and it's hard to understand. The story is complex and hard to follow in audio; had I known, I probably would have read this rather than listening to it.
The idea of one city both next to and partially superimposed on the next city is intriguing. The mystic nature of the third city Orciny adds more interest. Very good story.