The Thief is in Prison, playing endless fatal games of Prisoner's Dilemma with himself, failing to learn cooperation. Mieli, her spaceship, and her mysterious employer break him out, so that he can steal something for them, in-system on Mars, despite powerful factions who don't want him to. But when he gets to Mars, he realises that he has been there before, and left intricate clues to himself. He must unravel this puzzle, too, despite powerful factions who don't want him to do that, either.
This is a great post-singularity novel, buzzing with ideas. Exo-memories, body mods, hive minds, nano-bots, complex chocolate, the lot. All the apparently fragmentary plot-lines tie together in unexpected and interesting ways, and clues laid early on become important later. I suspect it might call for a second reading, since the clues tend to be swamped by the overall unfamiliarity. Despite enjoying it, I won't be rereading, however. Although the cover blurb has Charlie Stross saying "I think he's better at this stuff than I am", I disagree. Sure, it has Stross' great way of making a post-singularity world realistic and believable, but it doesn't have the wit and humour, and I never got to care for any of the characters enough.
So, great first novel. I hope later ones keep up the complexity, density and imagination, but add more wit.
This is a sequel to The Quantum Thief, and everything I said there holds here, too. It is a complex and rich post-singularity story, as the Thief and Mieli travel to an Earth on their secret quest, encountering nano-tech, and transcendent minds, and other horrors. But again, I found the characters unengaging: the only one I was rooting for was the ship.