Among paleo/primal/low-carb/ancestral-health books, the newly released The Paleo Answer earns a place within my top five ranking. It has many useful and up-to-date discussions of specific disease conditions and their relationships to nutrition. Since The Paleo Answer is just off the presses (or proverbial presses for the Kindle version, which I read on an iPad), it also has the advantage of being able to cite new research that has emerged since the release of Gary Taubes' monumental Good Calories, Bad Calories (GCBC).
The Paleo Answer is almost entirely about applied nutrition science. It mentions other lifestyle issues, but only in short treatments, so do not expect the kind of wide-spectrum discussion of lifestyle at the depth available in The Primal Blueprint by Mark Sisson. I thought the sub-title was misleading (blame marketing as usual). This is not a play-by-play gimmicky diet program. It is a highly informative applied science book (and sure, if you stop eating nasty toxins, of course you'll feel better in a few days!).
The chapter on vegetarianism/veganism is notably thoughtful, solid, and well-argued and might even be useful to recommend to vegetarians and vegans you care about. Moral issues of food production are touched on, but what Cordain really wants to make fully clear in this chapter, and I think he slam-dunks it, is that seeking better health is not one of the valid reasons to choose to be a vegetarian/vegan [I could not read the discussion of veganism and pancreatic cancer without at least thinking to myself: Steve Jobs, RIP].
It is nice to see an author who openly changes his mind based on evidence and further thinking, and Cordain is quite clear on points on which new evidence or understandings have led him to do so in the past few years. The discussion of vitamin supplements is important. Cordain argues that the most recent studies are trending to indicate that most supplements are somewhere between useless and harmful, although at least vitamin D and fish oil appear to remain positive. I thought his personal stories fit with the content and added something nice to the book, rather than being mere ego digressions. I particularly liked his tale of diving to get clean water from a high mountain lake.
The ample sprinkling of individual success stories from readers were also fitting. To Cordain's credit, he acknowledges that no amount of such anecdotes can equal scientific validation. Yet he goes on to note that ignoring repeating patterns of dramatically positive experience stories is also not very scientific. The balance of such repeating individual experience patterns constitutes a very loud signal that certain kinds of studies should be undertaken to check into these phenomena more systematically. He proposes some possible study designs along these lines.
The chapter on dairy shows some logical weakness. My reading was that all or almost all of the evidence it cites is from studies of cow milk drinking, but the author nevertheless generalizes those conclusions to all dairy products. I have had very negative experiences with milk drinking and stopped years ago, but no (noticeable) negatives with cheeses and heavy cream. Clearly there is a difference created with the separation into cream/butter and the bio-processing involved in cheesemaking. I am not saying those products are thereby cleared of suspicion, just that they are somehow different in their effects from milk itself and need to be addressed as such. I thought it was a black mark on the logic of the chapter (which also raises the question of whether similar problems are lurking elsewhere) that this distinction was not addressed and that conclusions based on milk studies alone were generalized to all dairy products.
Another weakness is the repeated and unexplained reference to "lean" meats as being recommended. I am not sure what this is about, but I guess it might be an artifact from the habit of bowing before anti-fat hysteria. Fat is the primary target of predators and ranks above lean meat in priority of consumption. Traditional societies the world over eat at least something approaching the whole animal. Your fellow h/g hunters would certainly be horrified if you started tossing out the most nutrient- and calorie-rich components of a kill in favor of boring old chunks of dry muscle. Both The Primal Blueprint and GCBC contain superior information on the subject of fats.
Only three volumes reside above The Paleo Answer on my current nutrition/health book rankings: The Primal Blueprint, GCBC, and The Paleo Solution by Robb Wolf (Wolf interviews Cordain about The Paleo Answer in The Paleo Solution Podcast #112).
In sum, that leaves the new Paleo Answer suddenly ranked above a large number of other volumes in this genre in my reckoning. I have gleaned good specific insights from books I rank lower, but the evidence-based quality and reliability of their advice is much spottier. I would definitely include The Paleo Answer in a top-five reading program on nutrition and health.