Aeon418
I looooooooove Dion Fortune's book! I read it after Chicken Qabalah, though, so I don't know how much I would have learned from it without DuQuette's introduction. I have read reviews of it recommending it for beginners though. She writes very nicely and clearly, minus the racist parts.
Over the years I've found that for every person who raves about Fortune's book there seems to be someone else who is bored to death by it. I guess it must be a stylistic thing. Some people just don't click with it. Personally I think it's a classic, but you can't please everyone.
Years ago I lent my copy of, Chicken Qabalah, to a friend. He read it. Enjoyed it. And quite naturally was ready for further reading. So next up I gave him my copy of Fortunes, Mystical Qabalah. Oh dear! He complained he could barely stay awake after a couple of pages. With hindsight it was probably a mistake to try him on Regardie's, Garden of Pomegranates. (Regardie can put me to sleep sometimes. ) And we fared no better with William Gray or Garreth Knight.
Several months later I picked up a book called, Qabalah - A Magical Primer by John Bonner. It's written in a similar format to Dion Fortune's book but in a more engaging and modern style. I was quite impressed with it. An added bonus is that the author is a Thelemite too.
I lent it to my friend, and bingo, he loved it. Since then it's been one of my main recommedations to people looking for a 'second book' after DuQuette.