For those of you who don't know, Ray Kurzweil is the man who invented Optical Character Recognition, along with various other pattern-recognition technologies. He is well-versed in what technology is theoretically capable of, and has spent his professional life trying to make it do these things.
I have nothing but good things to say about Ray Kurzweil, and this book in particular. The ideas that he puts forward may seem very optimistic, sometimes verging on techno-fanaticism, but nothing he is saying is negative. If he's right, the human race only has to survive until the 2040s and things will markedly improve.
However excellent I found the technological predictions made in this book, there are two points that brought it down to four stars. First, and a matter I admit is one of personal preference, there were far too many graphs to do with economy and business. This is an American book, so capitalism has to figure somewhere, and he is forgiven. The other point is that some of the speculations he is making are sociological ones and these are far more spurious than any technological speculations. However, they are not fundamental to what he is arguing.
All in all, an excellent, if at times overwhelming, read. I heartily recommend it as an introduction to transhumanism and futurism.