In The Body, Bryson does for human biology what he did for science in A Short History of Everything. In about 400 pages he attempts to provide a college 101 level understanding of pretty much everything you might want to know about your body. He mostly succeeds, although given the amount of information he is attempting to share the depth he goes into is shallow at best. Diabetes, for example, gets a whole paragraph in the book. Bryson is not a medical expert but the 40 pages of bibliography and end notes provide a hint at the amount of research he put into this book.
It's not quite as witty as I was expecting, as he mostly sticks to the facts, throwing out sentence after sentence of things you knew, things you didn't know, and things you probably should know in rapid fire succession. One example, your nose runs in the winter because air goes from a cold environment to the 98.6 degree sinus cavity, causing condensation. That's patently obvious, but I managed to get over 1/2 way through life without ever thinking about it like that. I particularly enjoyed his descriptions of early medical experiments, when researchers or sometimes outright cranks would test their medical theories on themselves, sometimes to fatal effect. Towards the end he gets a little ranty while discussing the US Healthcare system and how the richest country in the world manages to fail its citizens every day. It's something we should all be ranty about.
If you are a fan of Bryson you'll enjoy this book. If you've never read Bryson it's not a bad place to start.