Incarceron (Incarceron, Book 1) by Catherine Fisher has a lot of buzz -- I heard it recommended all over the place, and I borrowed it from my nephew last summer. Somehow I never got traction with reading it though, and it languished until I noticed I was about to return to Utah without reading it. So I got cracking, brought it on the plane, and finished it just after Christmas, which is really a glacial pace for me.
My problem was a supreme apathy about all the characters. There's the rich princess scheming with her tutor and with an inability to make emotional connections with anyone (she only cares for her father because she thinks they share some DNA), there's the Finn, a lost epileptic in the prison with the same problem (his only friend is his adopted brother, whose loyalty is proven over and over again, yet Finn doubts him every time anyone else is less than complementary). They are pushed around by circumstance, rarely making any decisions or actions, and when they do it is because of distasteful choices they make (be brave or be petulant? Hmm, lets be petulant!). I never got much sense of either of them, and only a little bit more from the secondary characters.
On the plus side, the two worlds are fascinating and my favorite character was the eponymous prison. I probably won't look for the sequel, but if forced to read it I'll just keep an eye out for sentient structures to identify with. C