This booked gives me a mixed understanding. It has both good and bad qualities. The author tries to make shaders easy to understand for people who are not programmers. He is successful in this endeavor by outlining how to use Render Monkey. However the author often glosses over details, and it leaves holes in what you are trying unless you open up his accompanied shader. It makes it feel like cheating. Also due to the age of this book, some techniques outlined no longer work.