This book is an excellent *hermetic* cabala encyclopedia - it is thorough, bringing together most of the information one would see in it, e.g. various attributions a-la Crowley's Liber 777 covering subjects such as the 72 fold name of god, the 42 letters name of god, seals, spirits, tarot, etc.
The book contains three major sections - the first is the encyclopedia itself in English alphabetical order, the second a Hebrew-English dictionary, and the third a gematric index which brings various Hebrew words by their gematric value.
There is a good bibliography, a reproduction of Crowley's Sepher Sephiroth, and a couple of interesting appendixes.
The major problem I see with this book is enormous number of errors in Hebrew - it looks like neither the author not any of Llewellyn's staff working on the book know any Hebrew. This includes not only spelling errors (which lead to errors in the gematria calculations, which means one should double check *all* Hebrew spelling and gematria calculations in this book with a good English-Hebrew dictionary), but also errors in basic material, e.g. none of the spellings of the 42 letters name of God brought in the book is correct.
So, indeed, one can benefit a lot from learning the correspondences and their logic, but still needs to cast doubts about what's written in the book and research for her/himself.
A secondary problem is with images - those are valueable, but many of them look pixelized, as if they were scanned at low resolution and enlarged.
And to repeat my emphasis from the first paragraph - this is a book about *hermetic* cabala, and *not* Jewish cabala. Jewish Cabala uses a different version of the tree of life (described in appendix C of this book), different attributions, etc.