As mentioned, this book was written from the materials and interviews made for the documentary on Zhang and reads exactly like that. While the author had access to Zhang, this book is not a collection of her interview with Zhang. In many places it was written almost like a script for a documentary and in other places the author filled it with materials from other sources. In fact there was surprisingly little from the actual interviews and the most disappointing of all, Zhang refused to divulge anything on what happened in the Xi'an Incident. And honestly, he had kept his mouth tightly shut about the most important details of the negotiations between Zhou Enlai and Chiang Kaishek in the years after that.
However if one is looking for a source that is easy to read to get all the facts of Zhang's life, this book would be a good reference. It is not one that gives the reader an in-depth understanding of the events because it lacks the analyses of the various events and therefore ended up looking a little disjointed and lacking a central thesis. But to be fair, the author never meant for this book to be one of an analysis of Zhang or any events associated with him, it is simply a documentary turned into a book.
I know of Zhang in my earlier readings but did not find out more about him. If this book has done anything for me, it has piqued my interest in him and he being young in those tumultuous years actually lived long enough to entertain a few video-recorded interviews that are available on YouTube (they are in Chinese though). His history has been presented in almost opposite ways in China and Taiwan. With this book as a start I hope to find out more about him and come to my own assessment of him.
(Find this book at Goodreads)