Any Taiji book begs the question "why does this book exist?" You can't learn from a book after all, so a book must either enhance what you get from your current teacher, or help you find a new one.
The typical Taiji book doesn't stand up to this question. It shows a form (usually poorly executed) sandwiched in a big wad of esoterica that is at best useless to a typical student and at worst misleading.
Master Liang's book, on the other hand, is among the best that I've seen that are available to the public.
First, of all, the examples are shown correctly. My pet peeve in Taiji books is bad posture and poor habits that should be purged after a few years of studying under a competent teacher, if not in the process of editing the photos. In contrast, master Liang's execution is, of course, impeccable. Second, this book contains guidelines for correct execution, which in most Taiji books is completely missing.
These two factors alone make it stand above any of the widely distributed titles. I would prefer a little more emphasis on readily observable criteria of correct performance. Armed with this knowledge, a student could readily critique himself, or a potential teacher. I've seen only one or two better books in this regard, and those were privately published.
Third, the book contains many demonstrations of applications for the 24 movement form which will be of interest to serious students and martial artists. Many people are unaware of Taiji martial applications because the abundance of grappling, throwing and other close quarters techniques makes Taiji fors difficult to interpret.
Finally, while even students of traditional forms will find much of value here, this book covers two of the most widely studied standardized forms.