The book is very comprehensive. I have not read through the complete book as yet, however, the big advantage is that you can go to any section/subject and get the in depth information you require at any particular time. The information is also very clear and delves in great depth into each subject.
I especially like the complete samples of various database(s) as well as samples and code where applicable on the companion CD. With the CD you have the ability to load all these items onto your computer and make the references available at all times.
The greatest asset on the companion CD for me is the PDF file of the complete book. As I get older my eyesight is not like it used to be and I have trouble reading many books and periodicals. Having the book on PDF format makes it very easy for me to read.