Interested in views on Mao: The Unknown Story

Half way through this myself - I expect the more interesting half, as his years in power are better known and more widely documented. Though I’ve read many books about Mao and the turmoil he was repsonsible for, my feeling is that this monumental work may well stand as the definitive account of Mao. What say you, and what think you of the book - those of you who have read it?