Higley books are ok, but it's obvious that some of the things he does are not techniques he developed over the years. It looks like he made it up on the spot for the book.
Plus, his stuff looks really heavy. I consider him to be more of a machinest than a modeler and don't care for his books too much. But there is some good info in them between the ads.
BTW - almost anything you can learn from a book is free on the web someplace.
- Paul