This was a rapid paced, exciting story, and fascinating to read. Ironically enough, not primarily because of the nanotechnology at its core, since, for much of the book, it was little explained and treated almost like background magic (Clarke's Law in action). I enjoyed when they did go into more detail at the end, but the fascination through most of the book was with the changes new technologies brought about in people and society. Things such as isolationist religions based on being "natural". Or the Gaia-Net, through which everyone is connected mentally to everyone else, networking off the nanoparticles around them, and how that affects attitudes toward privacy and even oral speech, which some have decided is no longer necessary. It also means that when the rogue technology starts bringing entire cities crashing down and deleting people in part or in whole, the horror and pain is experienced directly by others around the world. This may be a story based on a new technology, but there's a lot of humanity in it too. It's a book that will linger for a while. Recommended.