This short book is basically a run-through of the idea of motivation crowding, applied to a variety of policy issues. It's sensible stuff. He does not dispute that extrinsic motivation (not just money, by the way) has a role to play. In addition he argues that regulation can have a similar impact on intrinsic motivation as tying a lump of cash to an outcome. But he provides quite a few scenarios in which extrinsic motivation is likely to have little or negative effect.
The chapters are short (10-20 pages) and set out clearly and concisely how motivation crowding might work (or not) in a particular field. You can tell it is written by someone with an economics background as it reads differently to some of the psychological books on this issue (I'm biased but I prefer the economics slant). Each chapter also has references to other research at the end, so a useful resource too.
All in all a great, short primer.