I like the book.
That's all I know.
I liked it too, but it's been so many years since I've opened it up I don't think that I could really comment on it in much detail without re-reading it. One of Kisshomaru's struggles, of course, was how to present his father's teachings in a way that people could comprehend, and I do recall thinking that he'd done a fairly good job of it with this book.
For another side of the "administrator" image I'd recommend "Aikido Ichiro" - only in Japanese, but fairly readable nonetheless.