Brown leads us on a fascinating tour of quantum computing, from the background physics, up to the state of the art technology as it was in 2000. He explains lucidly, and in depth: in the first chapter alone we get a description of the differences between superposition, entanglement, and interference. He covers quantum algorithms, quantum communications, and physical implementations. He leavens his explanations with little vignettes of the scientists involved, but he concentrates on the physics for the most part. Even in the last chapter, where he covers some of the wilder and wackier ideas (from Penrose to Tipler) he is remarkably even-handed.
This is a jolly good read, if by now a little out of date on the implementation side. Time for a second edition, maybe?