As mentioned by other 1 and 3 star reviewers, this book is basically a come-on for Mercola's website, his nutritional typing test and other products on his website, combined with some valid metabolic food typing information.
However, you won't find in the book the food charts corresponding to the protein type, the carb type (now called the veggie type on Mercola's website) and the mixed food type (some protein and carb). Why not? Because Mercola says in the book that the charts don't reproduce well in the book, so you have to go on-line to his website to find the charts. The on-line links Mercola provides in the book don't lead to the food charts, though. Maybe they did once upon a time, but not now (March 2010). I had to put the web addresses in a google search. If you do a search on Mercola's website for these links, you'll have to do a lot of round-abouting to finally stumble onto the right pages, as of March 2010.
The book should be stand alone. That is, I shouldn't have to go elsewhere to get the basic information that I'm looking to the book to provide. That's the main reason I gave the book a one-star. If the basic material changes that quickly that it won't stand the test of time and requires updating on a website fairly soon after publishing, then the data to me is suspect.
The book through Mercola's website sells for $19.97 plus shipping. You used to be able buy the book here on Amazon for cheaper than Mercola's website (I got my copy in 2008), but not anymore. On Amazon, you can only get it used and the cheapest copy I saw (as of March 2010) was $40. If you're set on buying the book, then do so through Mercola's website.
If you're serious about metabolic typing, then go to the source, William Wolcott, in his book (with Trish Fahey) called "The Metabolic Typing Diet." Mercola refers to it in his book and website, as do other authors promoting metabolic typing. Wolcott and Fahey, however, won't make you jump through hoops to get the information you need in their book.
Metabolic typing works well for some, but didn't for me. Good for information, but didn't prove well as a way of life. The material in "Healthy For Life" by Rachael & Richard Heller, and Diane Schwarzbein, MD's "Principle" and "Transition" books work for me much more handily.
To be fair, there's good info in Mercola's book, but the slippery way Mercola goes about presenting it diminishes the quality of his product as far as I'm concerned. I'm giving my copy away in a used book sale but wanted to write a review before I did so.