A complete waste of time and money. This book is misrepresented in what it claims to be about. It contains very little information specific to embedded FreeBSD.
The author should have written much more about minimizing the kernel, limiting memory usage, device driver development, and flash storage issues - because these are the topics that are the most relevent to an embedded system. The discussion about using Tomcat, JSP, and JNI to provide web access to an embedded device - while important - is severely lacking.
A good book about an embedded operating system will explore the problems and trade-offs that a systems developer will have to make. It would also discuss getting the OS to run on a single board computer - such as one of the devboards listed in the FreeBSD ARM project. This book does neither.