I studied for the SCJP (OCJP) test for more than a year (on and off). I started with the
SCJP Sun Certified Programmer for Java 6 Exam 310-065
book, which was helpful. Once I finished, I felt that I needed more exam questions before taking the real exam, so I purchased this exams book. My exam scores (for the exams in this book) tracked at around 20-40% correct. Toward the end, I think I scored about 50%. According to this book, with such scores, I wasn't close to being ready to take the real exam. For this reason, I rescheduled the exam several times and I continued to study. The book told me I wasn't ready, right?
I finally got the courage to take the real exam. (My test voucher was about to expire, so I didn't have much choice.) The actual exam is *worlds* easier than the exams in this book. I scored an 83% on the real exam, but according to this book, I wasn't close to being ready to take it. I finished the exam with 45 minutes to spare, after several rounds of review. As another reviewer stated, there are fewer options for each question and the number of correct answers for each question is stated in the real exam. This makes the questions much easier! On top of that, the questions were more obvious. (Sure, there were tricky things thrown in (e.g., final and static modifiers) here and there.) To be fair, the book states that the questions are more difficult than those on the actual exam.
So, yes, the exams book did inform me of some exam 'gotchas'. It also scared me so much that I almost didn't take the exam. I would have preferred a book that was representative of the actual exam.