Overall, I find this book to be an excellent resource. It covers everything from power supply design to output stages. In addition, it intelligently attempts to cover all aspects of power amplifiers, including different approaches and topologies. One thing that is particularly pleasing about the way Slone covers this topic is that he discusses it intellegently, and scientificly. I found the section where he debunks audio myths to be of particular interest. Most importantly though, the author adds his experience into the book, by including rules of thumb, and the "really" important yet subtle details that come only with experience.
However, from a technical standpoint, this book is probably not for everyone. I've had an introductory course in EE (and will take my fundamentals course next year), and can understand most of what the author is saying. However, some topics seem heady, and I will probably not attempt to really read into those until after my fundamentals course. But I would say that if you have a good understanding of EE, this book should be no problem for you. However, if you don't (like me :), don't despair either, as there's really only a few chapters in the book that would be difficult. There's still a lot of material that one can understand with only a basic education in electronics.
But, in any case, I am definetly keeping this book with me, because anything that I need to know about building amplifiers is most likely going to be in there.