I enjoyed this book tremendously. The protagonist is a spaceship who is sentient—is conscious,—and has many human bodies through which she (who in fact is genderless) acts, speaks, interacts with her human crew, and each of which brings their own subtle colouration of personality. (In an interview, the author mentions that she became set on this idea when she realized that such a being could sing multi-part choral music by herself!) For most of the book, however, the protagonist is one particular human body who has been severed from the spaceship of which she is (was) a part, yet retaining the memories and sense of identity of the whole ship. This sounds confusing; it is somewhat, inevitably, but deftly handled, the writing highly engaging. (It is not the only instance in the book of confusing boundaries of identity.)
I also liked these two interviews with the author, one from her publisher (Ann Leckie on Ancillary Justice – Orbit Books – the one I mentioned above), and another from Locus Magazine (Ann Leckie: Silhouettes – Locus).