Although "Hyperspace" is fairly easy to read, and does have some interesting ideas in it, it's a little light on the science compared to other books I've read. That might be due to the fact that the subject matter is still in the theoretical stage. But, still, much of the book is anecdotal and many of the analogies used to explain the main theories are repetitive and off-subject. Plus, the book (and the information inside) is pretty out of date. Kaku often refers to things that might happen by the year 2000. This book is more useful for light reading than for really learning about unification theories and multi-dimensional universe models.