I don't think the book has anything beyond what you would see on the real GMAT. I think the only problem with Kaplan are the practice CAT's that can really destroy your morale because they score so low. Yes, Kaplan uses some tricky wording sometimes to mess you up, but there are going to be instances tricky wording may be on the test. Do I think Kaplan is the end all be all of study guides? No. But if you have access to it, and you study it diligently, it will help, period. Honestly, any study material, used correctly, will help.
EDIT: The only study materials I used were Kaplan Premiere Book, Kaplan 800, and about 100 questions from the OG. Then, I spent time on these forums answering the math and verbal questions posted. That's it, nothing more. But, I was very diligent in understanding where I went wrong, where I guessed and still go it it right, and where I took too much time. Then, focused on those. Its all about effective study.