Wrangham's thesis is that fire is what made modern humans. We didn't just learn to use fire because we were so smart: using fire actually gave us an evolutionary advantage which led to our being smart. In a nutshell: cooked food is more nutritious and easier to eat, thus allowing our evolutionary ancestors to acquire more calories for less effort, increasing their survival and also freeing up more time for things like inventing the wheel.
At first this may seem counter-intuitive, but Wrangham makes a convincing case, talking about the speed of evolution and how it's plausible that humans could indeed have evolved as a result of our control of fire, which Wrangham dates back to (possibly) up to a quarter of a million years ago. He talks about the physiology of chewing and digestion, how our australopithicene ancestors differed from us in how they ate, and crucial differences between human diets and monkey diets. Lots of talk about how the body handles cooked meat and vegetables differently than raw meat and vegetables. All of this is fascinating and convincing.
I think the second part of the book is weaker, as Wrangham goes into evolutionary psychology, which as usual involves a lot of speculation but without much evidence. Many of the later chapters felt a bit padded, like he had an obligation to bring in a social and cultural dimension to the argument. This I found less convincing -- we get a lot of talk about how cooking and food preparation shakes out in "primitive" societies, but this is all dealing with homo sapiens in our modern state. It's somewhat interesting but I don't think it really contributes much to his central thesis, which is supported strongly enough by the physical evidence.
Overall, a good food science and physical anthropology book.
Recommended for: Fans of evolution, monkeys, and cooked food.
Not recommended for: Creationists, vegans, or raw foodists.