I have skimmed this book. It's not really for fans, and it barely qualifies as "non-fiction." I'm not sure who it was written for. Maybe someone seeking a master's degree in American history?
It is an extremely well-researched collection of essays by the author. The first chapter contains some interesting tidbits of information, particularly about Loren Schwartz and the mysticism "mumbo jumbo" that had fed Brian's acid-induced Christ complex circa '65-'67. The rest of the book is like... I don't know how to describe it. The words "overwrought", "grasping for straws", and "minimum word count" come to mind.
You'd be better off watching this video:
https://youtu.be/NAh9oLs67Cw?t=64