I was recommended this book, and I enjoyed it. If you're trying to lose weight, then I recommend it. I already knew a lot of what's in the book, but that's because I'm odd and read a lot on the subject.
This is not a "diet book" in that it does not outline a dietary regimen. It does offer a lot of information about low carb diets and the science behind them. I was particularly pleased with the book's coverage of the history of low carb dieting. I had never heard of William Banting and the others mentioned.
All in all, I learned a few things and enjoyed the book. I'll probably read it again to help reinforce some of the material in my mushy brain.
Here are some links: Amazon's page, NY Times Review, random blog about it.