More blogger reviews here and here about Many Worlds in One. On the whole, both are rather positive, especially with regards to the writing itself. Both bloggers have issues with some of the assumptions and reasonings Dr. Vilenkin makes, though, and these issues are definitely to be considered. Not all theoretical physicists/cosmologists buy all the multiverse/eternal inflation arguments (at least as currently presented) that lay at the core of the book. I think it is always useful for us, as laypeople, to keep this in mind when reading any sort of popularization: experts often disagree amongst themselves over many issues.