I've had some AT sessions over the years, so I read the book to refresh my mind on the details.
This is tricky to rate. The techniques discussed remain beautiful and amazing. You can sense the author not only knows the ins and outs but has an extensive understanding of all the details. What bugs me is his putting AT on a pedestal above any other techniques. He advises against blending with other approaches to the extent of not allowing other terminology to be referenced. I understand not mixing, but blocking or even relearning terms goes a little far. "Inhibit" is a huge word in how he teaches AT. Whilst I understand his use as taking a pause before doing a movement so as to guide it correctly, it is engrained in me as a negative from my qigong training, where it speaks of erratic movement and inertia. According to him, I'd have to completely relearn that word, and thus through the baby out with the bath-water. Similarly, I know AT teachers who use yoga as preparation and similar, whilst the author poo-poos it as mediocre as well (well how it's taught in the west).
Now, this book is from 1990 – so a lot has changed over 30 years. Inclusivity seems more prevalent now. Also, the student is generally not seen as so dependent on the teacher as portrayed in this book. As such the book has merit in exploring the basic techniques and also reflecting on how far we have come since its writing in how we handle the learning process.