Even after having read a fair number of books on astral projection and lucid dreaming, this one still offered some fresh insights and practices I hadn't heard of. These are generally well-presented and get straight to the point.
On the other hand, the author seems rather credulous with regard to people's tales of the astral plane and so on. He seems thoroughly convinced that by willing it hard enough you can materialize your imagined beings and so on into this mundane old physical plane, and so on. He takes anecdotes from various people and traditions and concludes that these prove a wide variety of ridiculous claims and metaphysical theories.
In short: good practices, very, very poor philosophy, but well-written and worth checking out (it's only 150 pages).