I should have read reviews of this science fiction book before I bought it instead of just seeing that it was a favorite of the sci-fi crowd. It is of the hard science branch of the genre, and as such was not very understandable to my non-scientific mind. Its subject is bioscience -- "thinking" cells that can restructure DNA. I don't know whether any of this is even remotely possible. At any rate, as the story goes, a scientist injects such cells in his own body, and soon finds that they have multiplied and are taking over and changing him in drastic ways. Some escape through his sweat and infect others when he shakes hands with people. Before you know it, all of North America is infected!
The writing is pretty clunky, the events are highly unlikely, and Bear provides little character development. The ending, which comes abruptly, surprisingly veers into the metaphysical.
I wasted my time by reading this, but it was only an afternoon, so that's not too bad. I know there are much better examples out there of science fiction which is based on actual science. I would not recommend this one.