This is a short book with really good information. They get into the science enough for you to really get what is going on, but not so much that you get bogged down or cross-eyed from the level of detail. And they seam it pretty smoothly with the way to implement it for the reader (which I find clunky with Robb Wolf's "Paleo Solution" book).
What I also very much appreciate is that they'll take studies and then write up a "hunch"section, saying basically "based on data a, b, and c, it would be logical you could implement for your performance this way or optimize by doing that." I appreciate this so much because in so many health, fitness, and nutrition book you get authors with incomplete data making an extrapolation and labeling it as The Way.
The information in here is solid for any endurance athlete, CrossFit athlete, or general active lifestyle. The main exceptions I'd see is for the power athlete (powerlifters, weightlifters) and during certain phases of a bodybuilder's cycle. I won't get into my critique of those area, but it's enough to know that when you're working at the extreme end of strength training and in those metabolic pathways, your needs will be a little different over time.
Regardless, I think this is a book everyone interested in best health and performance should read. It's short, fast, with plenty of information to implement immediately.