Jim, as far as my own assessment: I don't feel like I've read enough of the book yet to give you a meaningful answer. I'll check back in after I've read more. At that point, I can give an informed thumbs up or down.
That said, it's an ASCAP-Deems Taylor award-winning book, so I think it's safe to assume that it's not simply a "fan overview."
Also, FWIW, George Clinton wrote the foreward and he gives the book his seal of approval.