I've read a number of books on Buddhism, and I can easily say this is one of the best I've encountered for providing a solid background and overview of this religion-slash-philosophy. However, the book suffers from something of an identity crisis, and lacks some critical information.
First off, the title says what this book is really about: *UNDERSTANDING* Buddhism. There is a wealth of information here, ranging from the basics (the story of the Buddha, the Four Noble Truths, cardinal precepts, etc.) on to explorations of the different branches (Vajrayana, Pure Land, Zen) and places Buddhism can be found in art and culture. This book is fantastic for learning about where Buddhism came from, where it is today, and where it may be going in the future.
However, the caveat is that this book is not so much oriented towards applying Buddhism to your daily life. The cover details really make it sound like you'll be getting lots of info on living in a Buddhist way, but it's just not true. There's a decent section on meditation, but by and large the book offers only vague guidance for putting the ideas you read about into practice. So, don't fall for the publisher and marketing hype - this is a book about understanding Buddhism, and not so much living it.
That said, the book falls flat on its face when it comes to providing some key information. The biggest example would be karma. Karma, a very important idea in Buddhism, is given less than TWO pages of discussion in a 400 page book! Yes, karma is a fairly simple concept, but anyone who has studied Einstein's theory of relativity can tell you that it's the simple things that are the hardest to understand intuitively. I would have gladly traded the section on Buddhism in art if it had meant there would be a truly good exploration of karma and its far-reaching impacts.
The long and the short of it is this: If you know little or nothing about Buddhism, and want a broad introduction, this is an excellent place to start. Gary Gach has a playful and enjoyable writing style. The book is chock full of interesting content. Just don't buy this book with the expectation that it will guide you in leading a more Buddha-y life. For that, I recommend a much more hands-on title, such as the excellent /Complete Idiot's Guide to Zen Living/.