Long-time readers will know that I'm a big fan of the Freakonomics franchise, having reviewed many of their previous books on this site. While none of the subsequent books has been as good as the first (which I highly recommend), they are all still very good.
When To Rob A Bank is as you would expect if you've read the other books: it's witty, it'll make you smarter, and it explores the counter-intuitive. Things that are accepted as conventional wisdom are turned over and often exposed for the fallacies they are.
One thing weird about this book is that there is no new content in it, however. It's just a collection of blog posts taken from the Freakonomics blog. As such, you can read the content of the blog for free, rather than buy this book. On the other hand, the authors have admitted that a lot of the content on the blog is crap (so this blog and the Freakonomics blog do have something in common!), and so what you're paying for is someone who has gone in and curated it to find only the best, most through-provoking posts.