This book has two sections: the theoretical material at the beginning, and the exercises. If you are familiar with Dr. Yang's qigong dvd series, the material in the beginning will look familiar. It's a nice summary of his introductory qigong theory. The second half, however, is what I find most intriguing. I do Yang Tai Chi, and what I see in Tai Chi Ball Qigong is a way of training familiar movements but with a slightly different twist. The ball makes the connection between the hands and the circularity of the techniques much more immediate.
The ball also adds a little weight to the movements. As a middle-aged woman, I lift light weights to stave off bone loss. The Western way of lifting weights, a way that "isolates" muscles, has never made sense to me. We don't use muscles in isolation in daily life, why isolate them in our exercise? Tai Chi ball allows me to use a light weight (the ball) in a way that is integrative and whole-body. It gives me a little bit or resistance while also training balance, fluidity, and flexibility.
One word of caution, however: If you wish to actually do these exercises (as opposed to reading about them from a theoretical or "tourist" perspective), assume you will also need to purchase both the book and the DVD. The photos are clear and good-quality, but I find myself unable to decipher the more complex movements from just photos with drawn-in arrows.
With that one proviso, I highly recommend the book to anyone wishing to add a new dimension to their Tai Chi practice.