The book gets 3 & 3/4 stars. It is a good, slightly dry discussion of the CR. The opening chapter, which covers the 'history' of it, is excellent. The following chapters are topical (art, economy, foreign affairs, evaluation) and are more uneven. The author has a slightly revisionist bent, trying to find the roots of Deng's opening inside the Cultural Revolution, but it is done with a light hand.
For a far richer, and really brilliant account of the Cultural Revolution, see John King Fairbank's remarkable Great Chinese Revolution: 1800-1985