This book is not a 'how-to' book. You won't be able to practice wicca just by reading this book. It is however, an incredible book on wiccan theory.
The book starts off with a brief discription of the various forms of Wicca that are practiced today. This is included mainly to give the reader knowledge that Crowley's view is of a particular kind of Wicca. That said, this book is valuable to any practicioner regardless of tradition.
It next gives a very realistic view of the origins of modern wicca. No fantasy here--the real deal! The rest of the book goes through all aspects of coven witchcraft viewed through the lenses of jungian psychology, spirituality, magick and personal experience. The author goes into detail describing exactly what goes on when, for instance, you are casting a circle or drawing down the moon. She includes what you should be thinking, feeling, and visualizing. The book does assume prior knowledge of the subject and if you are a beginner I suggest you read a good Wicca 101 book along with this to learn the "what" along with the how and why that this book provides.