I can't rate this book because I hate having to format my writing, especially in APA. As a result, I've developed a conflicted relationship with my lil' APA style companion. I will say it was recommended to me by my History of Books and Libraries Professor who is also the literature librarian at Yale... and not a damn thing gets past this dude. Up until now, I've been relying on Owl Perdue (http://owl.english.purdue.edu/owl/res...) which has been convenient but doesn't cover all the obstacles I've come up against in formatting my papers. So, I guess I'm grateful to the Concise Rules of APA Style for living up to it's claim of being concise. I'm sure I will be referencing it a great deal during my thesis and I definitely recommend it to students who really want to nail APA.
One of the most annoying things about being in the field of psychology is the necessity of adhering to APA's style guide. I'm a Chicago style girl to my bones, and find APA style alternately clunky and lazy. That said, the reason for the second star is that it's reasonably well explained in the concise rules.
Although this book was put out by the American Psychological Association, if you need to write correctly in APA style, either (a) master the 6th edition APA Manual or (b) hire a seasoned APA editor. I've been an in-house editor for over a decade and can make sure that your project is APA compliant.