The book does not, as the cover states, tell us how we choose. There have been many advances in neuroscience, but it still has not uncovered the mechanics of thought, or even how we store and retrieve memories. The book talks about some findings in neuroscience and talks at length (ad nauseum?) about the relationship between reward and dopamine release. There is nothing new here philosophically. Saying that our brain chooses maximum dopamine release is equivalent to saying that at any instance we do what we most want to do. In the epilogue, the book discusses how brain function might be related to quantum mechanics and multiple universes. To me this just underscores how little we currently know about the brain.
Overall, the book is not terribly well written. It jumps around a lot and is highly repetitive. The material could easily be condensed to the length of a magazine article.