I like two things about this book. The first is that it is very thorough and complete. Exercises, both stretching and strengthening, are included for basically every major muscle group or extremity motion. Furthermore, the book is divided up well enough that you can find what you're looking for fast.
Secondly, I like the fact that this book is evidence-based, meaning that it backs up what it suggests with references from the scientific literature. In fact, it's so good that it can be a great place to start a literature search from.
Know too that this book is mainly written for people who have some medical background of sorts, so if you're just an average reader looking for some workout exercises, this probably isn't your book. Rather, I feel like the book is better suited for athletic trainers, personal trainiers, occupational therapists, chiropractors, physical therapists, exercise physiologists, massage therapists, and so on. Practitioners looking for more info on the shoulder might also want to check out Treat Your Own Rotator Cuff -for more detailed ex's on rotator cuff tear prevention and rehabilitation.