Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Not worth the money

This book gives only the most basic of overviews for what you need to know for the real GMAT exam. Additionally, the math questions have many, many typos (for instance, they use a '+' instead of an '=' in the question), so it is impossible to know how to answer the questions. I didn't bother carefully reviewing the verbal section, because I was so disappointed with the math. I would recommend this book, only if you need additional practice math problems, and typos don't drive you crazy. I highly recommend the actual book from ETS and Kaplan books (the other 2 I used) for studying for this exam. (Also Elements of Style by Strunk and White may also be useful to you.)