I read the book last year and it was a pretty good read, especially if you like scifi and have played a variety of games on XBox, Playstation, or PC. Having seen the movie I felt it was true to the spirit of the book even though there was some minor variation. What was true to the book was very well done. Spielberg overachieved on this one I think. The cinematography and special effects were first rate, everything was "Hi-rez".
The book and plot of this film are not sophisticated, and if you are not expecting too much and are willing to be a geek, it is very entertaining.