I found this book very readable, despite its title. In fact, it's the most transparent of the several books which have appeared recently which use extra dimensions to unify gravity and quantum theory. This is a hot topic in modern physics, and I'd heard of 10D supersymmetry, 11D supergravity and 26D string theory. But I wanted to take the step from popular accounts of these things in magazines like Scientific American to something with more substance. This book does it. The math is powerful but does not cover up the physics. I learned that the world may be curved in the usual four dimensions of Einstein's general relativity, but could be embedded in a bigger universe which is flat! And Heisenberg's uncertainty principle, of the usual particle-physics approach in 4D, may be just the "bits" left over from deterministic laws in 5D! I like this book because it's pragmatic. As the author says, we need to understand 5D before we go off to 10D, 11D and 26D. I also like it because there are descriptions in words of everything he proves by math. The only negative thing about this book is that it looks a bit cheap. But at least it's affordable, and should appeal to capable students and researchers.