I've found various reviews that such much what I would, only with more gush, so I'll just annotate them.
Jaine Fenn has a review I like: as it says "SF but not quite Space Opera" which is what I was struggling to say: it has spaceships, it has travel between worlds (as that review says, "travel between worlds is too simple, treated rather like a short sea voyage" but that is fine; see comparison to Cecilia Holland), but these aren't handled the way you'd expect from yer typical male writer. For example, there are no loving descriptions of the hugeness of the ships or the power of their weapons; all that is left aside. It reminds me more of Floating Worlds by Cecilia Holland (which is brilliant; better than this; better than most things).
TOR has a review which I mostly like, and which pushes the pronouns issue, which I agree was well done (though in my recollection she gets it somewhat wrong: I think its just that Breq finds it really hard to tell gender, and usually doesn't care).
One of the nice things about the book is the way it surprised me. Example (somewhat spoiler-ish, so skip if you like): in one of the climatic scenes, JoT has just shot (one instance of) Anaander, and the other AM's have deployed the break-comms weapon, so everyone is on their own. The narrative voice (One Esk 19 I think) then heads off, and I thought "oh well, we're going to have a somewhat tedious fight scene". But no! There's no fight scene at all; One Esk just heads straight for the exit and leaves in an escape pod. Brilliant.
A criticism. The imagined empire doesn't really make a great deal of sense. The problem is that the "annexations" are brutal and violent, and remain that way even after the native population are subjugated. That's necessary for the flow of the book, but it doesn't actually make sense. That level of violence is known - now - to be counter productive and to Just Not Work. Its hard to imagine it being used as described.