Assuming you're talking about my book, I'd feel awkward telling you how good it is (because obviously I'm going to say it's great aren't I?!) If I'm to base such assessment on Amazon reviews, it gets an average of 4.5 stars. But you're best reading what other people have to say. I've linked lots of reviews in my post in the sticky thread.
Charles Lyons (SCJP 1.4, April 2003; SCJP 5, Dec 2006; SCWCD 1.4b, April 2004)
Author of OCEJWCD Study Companion for Oracle Exam 1Z0-899 (ISBN 0955160340 / AmazonAmazon UK )