depends on where you are at
I have read roughly ten books on the mental aspects of winning over the course of many years, who knows how many chapters and articles. It doesn't seem to matter much what the sport or pursuit is, the mental side of winning is much the same in my opinion.
The Pleasure of Small Motions is the last book I read and perhaps I would be more impressed if it had been one of the early books. However it seems to me that it is far too focused on ending negative thoughts and attitudes and replacing them with only neutral or arguably still negative attitudes. This book might be OK to get you out of a mental hole, I don't think it is a good book to make a champion.
My other key disagreement with this book is concerning the state we are trying to reach for optimum play. If you succeed in reaching the state the book seems to seek it is fairly easy to be rocked out of that state, sharked intentionally or accidentally. If you reach the higher state, you truly are shark proof. However Pleasure of Small Motions won't give you all of the building blocks to get there.
It is worth the read just as food for thought. If anyone accepts it as the be all, end all book on the subject they are stopping short of the tools best suited for success. This review is my opinion of the book of course. The general consensus of the threads I have read is that it is a must read.