I have read a number of Mary Wanless's books and used her ideas with my students. I had great hopes that she would be producing some new and interesting ideas, unfortuately not. Mary, in this book is just rehashing some of her old ideas - no new insights. Her writing style is quite labored and overly wordy - it could do with a good boiling down. If you want to purchase one of her books you would get the best value by buying "Ride with your Mind Essentials" which is excellent and more distilled.
I am a riding instructor and have recomended or give this book numerous times to my students. The contents are easy to understand and have profound insights into how the riders body must actually work be be able to successed in the difficult sport of riding. This book has boiled down her major ideas into an easy to find problem / solution format. I very, very highly recommend this book.