I also don't know this book first hand, so my opinion is based solely on how it appears on Amazon.
I sounds like a fascinating book, however, it also sounds like it would be more aligned with conspiracy theories, crypto-zoology and alien abduction than a factual book on hypnosis. Akin to books in this camp, it sounds like she finds evidence that supports her original hypothesis and then paints this as the whole picture, ignoring other contrary evidence and other possible interpretations of the evidence cited.
I'm not saying her hypothesis is wrong, I'm just saying her argument sounds very biased and non-objective, based on the reviews.
A good portion of the reviewers sound somewhat paranoid too, but that's another subject entirely!
I'd be very interested to read this book, but not at the price I found it for on Amazon.