This book is just fantastic. The writing, the world-building, the characters, the use of language - all excellent. The premise was instantly fascinating. An ancillary unit of an artifically intelligent space ship seeks vengeance against the similarly fragmented leader of a galactic empire? I mean, do I need to say anything else?

There's a lot of unique perspectives on individuality and free will in here. Breq is simultaneously an ancillary with her own thoughts and impulses, but with recollection of being part of a collective unit. Her narration often switches between first person singular and first person plural, then back to first person singular - but a different "singular" than the original one. It's a complex structure that could easily become tedious or gimmicky with a less skilled writer. Breq is also a subservient AI who is subject to orders that sometimes contradict each other or her own desires. The conflict of her individuality versus the directive creates one of the more interesting plot arcs in the book.

The world itself is brilliantly crafted, with heavy influences of ancient Roman Empire-style conquest and social structure. There's conflict between the primary society and its colonies, but also within its own mission statement. The one complaint I found in the book is the stagnant development of society and technology within the 1000 year time span.

Spoiler

I'm skeptical that no other attempts at developing the advanced weaponry or contacting the other civilization were successful. It's also a rather stagnant progression of Anaander's internal conflict, if it takes so long to finally come to a head.

The use of language also can't be ignored. There's the obvious pronoun thing, where the Radchaai don't use gendered pronouns, so everyone is referred to as "she." Breq has difficulty in correctly "gendering" people, as the multitude of cultures under the Radchaai empire all have differing social cues for gender. But, to really make it interesting, when other characters are speaking in different languages, there are gendered pronouns. It's indicative of culture conflict between the empire and the colonies, and also a very clever way of addressing that idea when everything is presented to the reader in English. I also loved other uses of language in the book, like the fact that "civilized" by definition only refers to Radchaai, or that double speak is imperative in keeping off Anaander's radar.

The relationships and characterization! They were so complex and rewarding. Breq's loyalty and love of Lieutenant Awn, Skaaiat's conflicting feelings of duty and love, but especially Seivarden's progression from apathy to antagonism to respect to absolute devotion toward Breq. It's wonderful character development, and even Anaander ends up being a lot more complicated than you'd expect.

Okay, enough gushing. I can't recommend this highly enough, and I can't wait for the next book.