I wouldn't say it's the best book, but i enjoyed it. He sort of came up with this Valsalva theory himself, and like all control methods it doesn't account for all speech related issues that trip us up, but I enjoyed the book. It gives good background on the mechanics of stuttering and his method integrates a lot of other well accepted opinions. I still think the goal of control over communication does more harm than good, but it's definitely an interesting perspective and i'd recommend it.