This book contains allot of very basic information on how to hold the jo, and it contains a good amount of images detailing the end position of each technique within the book, as well as comparisons with exsisting karate techniques.
The place this book falls down is that it is designed for people who already know karate, which as much as a pitfall for none karate practitioners is also a very good recommending point.
There is allot to martial arts that can't be taught by a book and this book doesn't attempt to teach those things. Instead it gives you information that would be intresting to none practitioners but to already exsistant practitioners it provides an excellent home working guide for some references to the basics of using Tonfa.
Just as a Kata is a tool for your to improove your fitness and technique when your instructor isn't there to teach you, so this book is an excellent tool to improove your very basic tonfa work when you are alone and your instructor isn't there to teach you.
So in simple form
If you are a practitioner of pretty much any art and want to see some basic Tonfa positions with descriptions, this is a great book.
If you want to learn tonfa without any prior experience, using this, as with using any book, will ONLY give you positions, not any gearing, force generation, correct movement actions, or muscular tension patterns.