Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Definitely worth the money!!

I studied by mostly using this book and scored a 750. I agree that it isn't exhaustive, but it gave me a great idea of what to expect. I like that it isn't this huge, thick text...it kept me from being too overwhelmed, and I was actually able to read the entire thing very quickly. The practice test is helpful as well. If you review your 'best practices' texts, intro class notes, and know your bell curve, you should be fine. As with anything, you can't expect one book to completely prepare you.