"Lucid Dreaming" is a skill and therefore can be learned. The whole concept is about becoming conscious within your dreams while remaining asleep. I reckon anyone interested in the book has a rough idea of the concept, so I won't bore you with that.
LaBerge is the foremost expert on the subject of lucid dreaming and the first to conduct scientific research into the topic. His book describes various ways how to attain consciousness within ones dreams. He gives examples of the utility of lucid dreaming and the book concludes with an outlook that I would describe as a mix between esoteric and philosophical.
Still, I don't regret the purchase of the book at all. However, don't be mistaken, it's only an introduction into the topic and by no means an extensive tutorial into the techniques (even those mentioned in the book).