I usually avoid diets that tell you one type of food is bad and another is good. Fads never work and can be detrimental to your health. This book, however, was pretty well written and filled with common sense (as are most decent diet books). There's alot of interesting information about different types of fats and processed foods. It's also geared towards changing your eating habits, and not just dropping pounds and losing inches.
I still have to check out some of the studies they refer to though. Also, some ingredients are hard to come by, this being an American book, but it's not that difficult to find alternatives.
Buy this book if you want to add to your collection or if you're looking for a bit of inspiration (especially recipes). It does actually work (but don't forget to exercise too!). If you've got some common sense, though, and know a reasonable amount about nutrition and different diets in different countries, you'll probably get by just fine without it.
Mind you, at this price why not just buy it anyway?