"Decent, but derivative."
How We Decide is likely to be a good introduction to the theory behind behavioral economics and topics within. It would be a nice book to check out if you've read Freakonomics, but not much else on similar topics. If you're a veteran of such books, you may consider taking a pass...
When listening to this book, I was frequently deluded in to thinking I have read it before - despite the fact that I hadn't. It focuses largely on studies that are also covered in similar depth in many similar books, comes to similar conclusions, and in many cases provided no additional insight over the other books. This is not to say there was nothing in it that was new to me, but that I felt that I knew perhaps 2/3 of the material already. If you've read such books as The Logic of Life, The Wisdom of Crowds, Predictably Irrational, and other similar books, How We Decide will rehash many topics, and bring a few new ones to light. If you're unfamiliar with them, it is as good a place as any to start.