When you first get this book, it seems a little thin, but if you want to help someone to learn to drive without falling out with them for the next 12 years, it's well worth it. However, this book is designed to be used with a qualified driving instructor (ADI), and is not a guide to teaching learners how to drive. What it will tell you is the best ways to give a learner extra driving practice and therefore help them pass sooner and become a more experienced driver. If you learnt to drive a while ago, can't remember what it was like or learnt to drive when the roads were a lot quieter then you need this book. It will help to see the experience from the learner's point of view and teach you to be patient, and that is likely to help both you and the learner.
The book is set out in short sections with bullet points and big colour diagrams that really help to explain the situations. However, a large part of the book is the logbook, which you can only use if the ADI agrees and is available for free anyway.
As the official guide it covers all the important topics and all the information is up to date. However it leaves out a lot of information such as how to correctly perform manoeuvres or approach junctions, concentrating on what the learner is likely to do wrong and how to deal with it. This kind of information comes from a book like Driving: The Essential Skills. If you use both books together, learning to drive should be a lot easier (and you'll pass first time like my learner).