This is not so much a book of ideas to read as it is a collection of exercises for developing reflective teachers. There is a variety of activities to do on your own or discuss in small groups. In fact, it is best to use it as a workbook in small groups for discussion (in conjunction with a textbook). Although some exercises may seem simple at a glance, I believe that doing them with a group can result in many interesting ideas. That is not to say that there is no "information"... there are short articles included, which I found to be very informative, and some of the activities are presented with a definite point of view. In fact, you could think of the activities as illustrations which Adrian Doff uses to show you what is good and bad teaching.
I would definitely recommend it for any a ESL training course. It can also be used during teaching practicums as it has questions at the end of each section that you can use to reflect on your own teaching. Although it is a bit scant in the area of speaking (my specialty), I found it very informative in general. Many aspect of language teaching are covered, from teaching techniques/activities to creating tests and using classroom equipment. Some I had not even thought of... like using the blackboard! The layout of the book is nice, and there are some cute illustrations. Having taught ESL for two years, I found this book to be a thought-provoking and fun refresher!