Gideon the Ninth, Tamsyn Muir
Worth reading for the language itself. Check out that first sentence.
What follows is an incredibly promising story, warped imagination, drama, dialogue, tension, wit and jokes until the last page. It's just that that last page is a bit disappointing, the resolution feeling a bit cheap.
It's good enough that I'm reading the sequel and enjoying it. This is like Neuromancer meets ummm... The Addams Family? Never seen anything like it, and the flaw I feel a less challenging book might have avoided is more than made up for by Gideon's irreverent literacy.