What it says on the cover : 70 solutions to common problems. The recipes seems less advanced to me than what you'd find in most of O'Reilly's Cookbooks, for example, but they're varied enough and the short time you'll need to read the book will probably prove profitable.
This book was a recipe to boost my knowledge of Rails development. Sometimes it has simple recipes, sometimes i get stuck with more complicated ones. All in all, I loved it.