If you are expecting to learn Java 3D programming, then you won't find much help from this book. This book is talking about the pioneering idea of '3D Virtual world for user interaction', instead of the current '2D GUI'. There are more principles than implementations in this book, which is the way I like. I will not use Java 3D to build any real applications, but Java 3D is purer and easy to grasp the concept than OpenGL or DirectX.
I guess many of the code and concepts of the book is coming from a research project on 3D user interaction, in Rice University. This book is a little bit too much focused on this special 3D framework.
And I don't like the writing style of the author. This book is somewhat difficult to read (I am a foreigner), the author uses lenghy words to describe a simple idea, and most times in a objective manner instead of a subjective manner, lists a lot of fact without giving a good reasoning. The reason for such a writing style maybe also because this book is comming from the result of a research project.
Bottom line: This book is excellent for who already have some 3D programming and OO pattern design background, and want to build/study next generation user interactive method. Currently not much people think 3D GUI is important, but I believe 5 years later VR, 3D GUI will become more and more popular. This book is really a pioneering work.