There are tons of books about virtual worlds, especially about second life. All of the ones I have seen (before this one) were more or less instructionbooks for people who don't have a mind of their own to click around in a virtual environment and collect some basic information, or artefacts of self celebration of residing avatars.
This one is nothing like that. Guest focusses on his personal research and experience in these environments, for the biggest part in secondlife.com . He gives us an interesting and sometimes even touching account of the fact, that these worlds are populated by real humans and not by game characters. Even for me as a long year (but not veteran) player of this environment, the book had an enormous amount of new and fascinating facts on the history of SL, that usually would not get published, since Guest partly approached it from the underground and not from the shiny surface.
I regrett I never met him there...