Take a look at the Kindle Preview pages on Amazon and then decide whether or not you want to spend money on it. The general test taking section looks like it was written for the verbal section of the SAT or general GRE. It talks about conceptual clues, prefixes, and avoiding answer choices with extreme ideas.
The actual math study guide looks way too basic to be of any use. You probably want a book that teaches you problem solving strategies, not a book that spends half a page on a visual description of the graph of cosine.