I read the book. I think it had a lot of good data but don't agree with its ultimate premise that we should all be high fat, high protein ultra low carb. Also I take issue with the idea that the average substantially overweight person can "eat to satiety" and still lose weight as long as carbs are fully restricted. Trust me, I can pile down 1000 calories of almonds like it's absolutely nothing at all.
One of the reviews on amazon challenged with a good point I don't recall being addressed which is that modern meat is very high in saturated fat; i.e. it just isn't the same as the meat from yesteryear. The way around this is organic grass-fed, which many paleos like, but have you seen the price of it? Very expensive. I do eat some of that stuff but my diet primarily of that would break the bank. I see tandorchicken refer to a study about sat fat and heart disease, but AHA continues to recommend a limited intake of it. I can only assume they are aware of a meta review of its effects. This is similar to the talk about cholesterol in food. I'm not sure how to reconcile the recent view that cholesterol in food isn't such a big deal after all with AHA's continued recommendation to limit cholesterol-high food.
What the book did for me is have me take a serious look at my macros and my source of food. I will say right now I'm pretty darn low on processed food. I also have upped fat intake a lot (about 35% of calories), and there is fairly conclusive evidence that a high-carb diet is bad for triglycerides and blood pressure; it really is a bad diet, so the book helped me to think a little outside the box. I am 40-45% carbs, though still, but it's not processed (as long as I don't include canned beans without sodium as not processed!).
I've seen some mainstream stuff recently as well (maybe wasn't paying attention before) about low-fat diets and their injurious nature. They were touted for a long time but there's no evidence they really help fat loss, and there is evidence that they cause harm to the body (aforementioned triglycerides). Some continue to adhere to them ignorant of these ideas, though, and are still scared of fat. Taupe makes a fine point that there are no essential carbs. It is thought we could live long term on nothing but protein and fat. However, I am positive many still see fat as "worthless", as in "I already have some on my body, so why do I want/need to eat more of it?".
A recent staple of my diet is avocados. I eat them like I'm paid to. Those and almonds regularly create my lunches these days.
Drawing parallels between diet of people years back and how that is relevant to us is very hard. We know little about cavemen, for example, other than that 40 was probably old age, so even if they were all going to have heart disease at 50 it didn't matter.