This is sort of the 'Consumer Reports' approach to sorting out the various products that are available. A comprehensive and scientific method of evaluating hundreds (1500, actually!) of products, all of which claim to be 'the best'. I sell nutritional supplements and was delighted to find that my products are among the very few ranked as the best in this evaluation!!
I have read criticism of this book by some who are concerned that there was a connection between the author, MacWilliams, and the USANA company, which is the one of the very few "Top-Rated" products (MacWilliams himself acknowledges that he is a consultant for several manufacturers). After reviewing the evaluation methodology, and considering that products from 5 other manufacturers, with which MacWilliams has no relationship whatsoever (as far as I can determine) are also "Top-Ranked", I think it is clear that there is no indication whatsoever of any conflict of interest. Some have criticized that one of the researchers who developed the "blended laboratory standard" against which the products were compared is on USANA's Medical Advisory Board (this is clearly stated in his bio in 'The Comparative Guide' so there is no attempt to hide this information). But, every one of the researchers who participated in development of the "blended laboratory standard" are experts in their fields... OF COURSE their advice is sought by many companies in the industry. Those who seek to inpugn this publication are most likely venting 'sour grapes' that their product(s) didn't fare well in the comparison... perhaps their effort would be better directed at improving the quality their products, rather than trying to discredit what appears to be such a fair and balanced evaluation!