This book tries to be two different books. The first part is how muscles work, how forces interact with muscles, bones and joints. There's an interesting chapter on posture and stretching nerves (didn't know you could do that!) Basically the first 80 or so pages are biology and science.
The second part is the actual exercises. There lots to look at but they are technically termed such as "trunk lateral shift" and "lateral flexion (with overpressure)". They are nicely illustrated but do not indicate what is being stretched.
I have given this 3 stars because it is not really what i was looking for. I'm a casual gym user and cyclist commuter so i don't need to know the science. On the other hand, if you're an instructor, professional or lecturer then this book will probably be very good for you (5 stars).
If you want something for the casual user in simple terms, check out "Stretching" by Bob Anderson.