I read this book and refer to it often. I think its excellent. I am using the ARC method with long arms/legs and flexible. I bought this book after following a flat swing path, which was disastrous for my game and went from a 16 HCP to 8 in about 2 years fate reading this book.
The ARC swing is somewhat un-intuitive and its very much from the ground up (feet, legs hips, then shoulds/arms) and takes a good amount of practice. The hip movement is a little tricky as well, for me at least. You need to practice and play often. I fight the tendency to lead with the upper half of my body.
I think this book makes alot of sense if you think about how leverage and path work and relate to given set of conditions (body type)