Caveat: the version I read is from 2000, and I know it's been revised. However, the revision notes all seem to imply that nothing was removed, only added, and so I feel the majority of my critique here will most likely stand.
tl;dr: skip it This book feels like it was written as a college essay with a minimum word count that could have been a 'recommended reading' pamphlet, because anything useful was a cited quote from some other source and the rest was repetitive bloviating, hero worship, and personal philosophy/opinions far removed from anything specifically useful to animators. He spends a lot of time condescending the reader and social signaling, to boot, which leaves me with the impression that (all things considered) this book cornered the market because it was the only one with all the keywords in the title for the first ten years of its shelf life.
There are plenty of excellent books out there on developing characters, body language, cinematography, and acting theory that you could read instead and get more out of. If you're enrolled in animation classes, most likely they've already covered the basics of performance touched (lightly) on in this book.
If you really want to read it, here's the highlight reel: - Skim the numbered headings of Chapter 1 (Seven Essential Acting Concepts) - Start reading from Chapter 5 (Movement and Body Language) to 9 (The Form) - Skip to the acting analysis - Make a decision about which sources sounded useful along the way, and move on to reading one of those