A good introduction, but very rudimentary.
There are a couple of gems in this collections, notably the articles by Richard Smoley, and the one on Mystic Christianity by Nottingham.
The chapters about Blavatsky, Guenon, Gurdjieff, and Schwaller de Lubicz were quite interesting as well, as I have read the work of all these individuals but never really knew their stories.
Other than that, I found most of the chapters in the middle of the book to be pretty rubbish.
Overall, I don't think this is a book worth owning, as it is too shallow to merit a rereading. But if you are new to esoteric studies, this could serve as a good starting point.