Good book, but unfortunately it doesn't cover all exam topics. Also, simulated questions are more difficult than real exam.
We all know how it is: the aim of any certification program is making money. Sun makes a lot of it selling the exams, the authors of this book make quite a bit of it selling the book and hopefully you at the end of the chain make a little bit advertizing your skills.
If you are of those weirdos who ,like me, consider programming a fun and fascinating adventure instead of a business, you will probably have a hard time enduring the induced claustrophobia.
Anyways, the authors of this book made a very decent job in covering all the details, useless tricks and nuances you will need to pass the 1.5 exam. (And no big deal they did, since they developed the exam). You will also find a lot of practice questions and two exams on which you can work to hone your exam passing skills. In the end, this is an excellent tool to help you pass the SCJP, just don't make the mistake of using it to learn Java programming. Head First Java, from the same authors, is one of the best choices to do that.