I may be rather peculiar as a reader; some people read for the plot, but I get lost in the settings and the characters. In this respect, The Unnaturalists was a masterful work. The setting was unique -- an alternate, magical London. The characters were convincing and, while not perfect people, real enough that you didn't question their motives, which makes them -- in my book -- perfect characters.
The one thing I would question about this book is its target audience. While I think this was written for people in their teens, there are aspects of the plot which I think would evade some younger readers. The characters -- especially in their relationships with each other -- are very complicated, and there are many facets at work here that do not lead to a pat ending -- and, in fact, there is no "pat" ending and in the other reviews I have read, I believe that this was unsatisfying for some of the young readers. An adult reader, however, would not be disturbed by it ... I'm afraid that is all I can say without needing to tag the spoiler flag.
I look forward to reading other books by this author.(