The author has made the "VHDL summary" appendix available on his website, and unfortunately the book uses the non-standard libraries "std_logic_arith", "std_logic_unsigned" etc.
For a beginner I recommend a book that uses "numeric_std", which has been the IEEE standard for about 20 years.
The library has a significant impact on the code, so the selection is important.
I want every beginner to know that there is a choice to be made here.
At work, we are only allowed to use numeric_std.
It is much easier to learn numeric_std from the beginning than to switch to it later.
I accept that some designers use std_logic_arith, but I think it should an active choice and not decided by randomly getting a book to learn VHDL.
Look at "The designer's guide to VHDL" by Peter J. Ashenden:
http://www.amazon.com/Designers-Guide-VHDL-Systems-Silicon/dp/1558602704
Unfortunately, it is normally impossible to know which libraries a book uses without looking at some example pages.
Reviews normally don't mention this.