I understand why this was a USA Best Book Award Finalist. If you don't have this book or a similar one in your Taiji (Tai Chi) library, I highly recommend this text by Shou-Yu Liang and Wen-Ching Wu.
Simplified Tai Chi Chuan is excellent for anyone looking to start or improve their Yang-style Taiji methods and skills. It has everything from base fundamentals (such as qi/chi and other philosophies), history, stretches, caution notes on avoiding over-extensions and strains, and a visual walk-through of how to perform 24 and 48 forms.
I would emphasize the greatest strength is the applied combative/defensive techniques for 24 form. Although many Yang-style practitioners know how to use it meditatively as an exercise, only a select few know how to apply these techniques against a sparing partner. This makes the text a fun read, especially if you enjoy learning about the applied movements and techniques of any martial art.
Although it's sad not to see applied techniques for 48 form, it is understandable, as it would make the book incredibly long. Additionally, since 48 form is a combination of various Taiji styles, it makes sense that examples and methods are not included, and would need a number of credible authors to explain how to perform each technique in sparing or defense. [From what I know, 48 form is used as a competitive performance art, where judges rank performers based on how well they execute each move and their form overall.]
Still, this book is useful for learning Taiji as meditative exercises or if you are seeing something a little more vigorous and applied. If you are looking for deep, pages-long, expansive philosophy and theory, then I suggest another text.