Make no mistake: this is a very good novel by any standard, and by the standard of first novels, it's exceptional. It's ambitious, genuinely science-fictional (in the space-opera rather than the mundane-sf mode), well-written, well-characterized, and presents a vision of a group of human cultures that are nevertheless very alien indeed... and not just stereotyped Earth cultures transposed to space. It gives us an colonialist, hierarchal military dictatorship with imperial aims; it gives us the perspective of people attempting to work within and against that dictatorship without ever becoming cartoonish in its depictions of cultures and characters. It addresses the complications of social rank, gender, and ethnic prejudice without becoming simplistically polemical.
It has a series of very cool posthuman Big Ideas, extrapolated and fleshed out with a skill far beyond what I'd expect of the typical first novel. Too many space operas I've read recently take as their starting place the somewhat mined-out turf of Niven-or-Varley Belters or Cherryh's deep-space merchanter and space navy culture, and while some of them take those ideas in fascinating directions, it's refreshing to see a book that does something fresher. This book arises from a more Le Guinian paradigm--a sprawling posthuman but not postcolonial government clinging to its empire through military might and ruthlessness, expanding through and annexing human-settled worlds and butting up against encroaching aliens. In a bit of Banksian ambition, this vast sprawling civiliation is populated by people--and A.I.s--who can be in twenty places at once through technology that allows the replication of selves, and communication between those selves.
(I have a little bit of the same problem with this book that I had with Altered Carbon--to wit, brains and minds aren't actually separable that way--but what the hell, it's an established S.F. trope, let's run with it.)
The first two thirds of the book have a nice, carefully-thought-out plot that is one part revenge story, one part political thriller, and one part planetary romance. It's replete with loyalty, betrayal, paranoia, and at least three breathtaking moments of Oh no you didn't.
Somebody once described what I write as "comedies of ethics." That applies to the current book as well.
Alas, some structural problems derail the final third of the book. A long, glossed-over time break happens, and does not seem to affect a relationship between two primary characters sufficiently. (There is a small effect, but our relationship with someone we have known for a year is different from the one we have with that same someone when we've known them only for a month or two.) And after that break, the story begins to feel somewhat rushed and arbitrary. Rather than acting, the protagonist feels acted upon--sometimes coincidentally. She gets a lot less clever suddenly, too, so that she can fall prey to certain dictates of the plot.
And the plot itself--and the character motivations of various allies and antagonists--abruptly become confusing and opaque, leading to a climax and what should have been a stunning reversal of fortune that sadly lacks the emotional impact and catharsis I craved.
Still, there's a very nice inventive space fight that shows Leckie's potential to develop Cherryh-like space battle chops in a couple more books, and there's a sequel hook to die for.
Ancillary Justice at its best establishes Leckie as an heir to Banks and Cherryh. At its weakest, it's still one of the best first novels I've read in five years.