The book is a meta study of the research done on the so-called metabolic disorders (obesity, diabetes, heart disease). The research doesn't talk about evolution and cavemen, but rather health markers, hormones, and metabolic processes.
I've been eating a less -ahem- tribal version of this for 4 months, and the results have been pretty remarkable (if entirely anecdotal).
I have lost a large amount of weight, my skin and hair are much improved, my digestive functions have normalized after a lifetime of trouble, and I'm no longer tired all the time.
I haven't been sick since I started, but 4 months isn't exactly long enough to suggest anything in that respect.
What I do differently from the tribal version in the article is
1) I don't exercise (yeah, I know, evil, but I just don't feel like it yet)
2) I eat tomatoes and cheese and cream
3) I don't fast; I eat whenever I'm hungry. Interestingly, I'm only hungry about twice a day now, rather than 5 or 6 times a day which was the norm for me before I started this experiment
4) I'm super relaxed (pragmatic?) about the whole thing. I haven't seen the light or anything like that, I've simply had some really good results with very little effort.
There is a blog at http://www.marksdailyapple.com which has plenty of interesting articles, as well, but the Gary Taubes book is the closest thing I've found to proven health benefits.
Anecdotes are not evidence, but for me, it's been 13 months. Triglyceride count is 40mg/dl, and I seem to have avoided four serious flu epidemics, the last around christmas (so my white blood cells are low). I do very little exercise, tomatoes once a week (bloat afterwards), eat cheese and cream, but no milk. I also noticed the reduction to being hungry only twice a day.. imho, that counts as basic intermittent fasting though (if you skip the morning meal).
Unlike the caricatures in the article (and Taleb, from another somewhat sardonic writeup) I don't take it very seriously.
As for the digestive part, this is quite remarkable, and I can only explain it by saying that everyone (or at least me) is borderline coeliac/lactose-intolerant.
I've gotten sick twice, but my immune system took care of that rather fast. I barely experienced any symptoms and made recoveries within a day or two, something that never happened before
Eating 2 meals a day was bad for me because I'd feel a lot groggier eating over a 1000 calories/meal to meet daily requirements
I speculate that maybe I eat less now than the daily requirements on occasion. I have a large amount of fuel stored, which seems to be easily accessible these days (to judge from the rate at which it is being consumed, anyhow).
Perhaps when my weight has normalized I'll get hungry more often.
Personally, I solve it by replacing carbs with fat - but without actually measuring. I just eat plenty of flavorful food (and drench my veggies in butter).
Mark Sisson has written about fats in the diet here:
The general idea floating around on his forum seems to be "when in doubt, eat more fat".