The book is nothing if not comprehensive, and if you work in the field, it is a useful reference to have close at hand. However, I would not recommend it to a student, since there is a good chance a student would be bored to death by the time he slogged his way through this. Thurston's notes (NOT his book), available for free from MSRI are available for free from MSRI, and are vastly superior as an introduction. Various survey papers by Vinberg (including the one in the Russian Encyclopedia of Mathematics: Geometry: Volume 2: Spaces of Constant Curvature (v. 2) are very lucid, and bring out the beauty of the subject much better than the book under review.