There is a ton of information in this book, and the majority of teachers will never need to use much of it. Still, it's important that all teachers, especially those in middle school and up, have at least a cursory knowledge of most of this information. My only real complaint about the content of the book is that the statistical information could have been presented in a more thorough and direct format. All of the information needed to introduce concepts like z-scores, standard deviation, stanines, and so on are presented, but the manner in which the material is discussed could have been organized better.
Other than that, the book is well-written, extremely informative, and serves as a great introduction to the concept of testing and what it does.