Less a coherent book and more a collection of thought on various topics. It's a very interesting read, and they use their economic background to look at things in a different, and often refreshing way.

However, I didn't feel this was as good as their first book, Freakonomics. It feels less researched, and more as if they just wanted to get a second book out the door. There were a number of places where I felt they were influenced by their own personal biases instead of drawing a really objective conclusion. So, still an interesting read, but if you haven't read either I'd recommend the first book instead.