This book is a very good summary of solar water heating, whether you just want hot water or you want to use it to heat your home. There are many books that contain most of this information, but this one is more up to date than others I have seen. The biggest added value is that the authors have years of experience, so they warn you about approaches which seemed like a good idea 20 years ago, but have not worked out.
What is really missing for me is the information needed to design a sophisticated system. For example, they mention early in the book that some controllers can be accessed on a network. I expected to later find some description of these, or a source for them, or even just a brand name mentioned. None of that is in the book.
In summary, I would highly recommend this book to someone new to the idea of solar water heating. It would probably also be good for a professional in heating or plumbing who wants to add some new business. If you are like me, and have already read and thought about this topic, what this book adds is a little disappointing.