I have to agree with the sentiments presented elsewhere. This is a rather terrible text when it comes to teaching music theory. The exercises are extremely repetetive, and the only thing that could possibly make this book useful would be a good teacher. As it stands, the concepts don't tie in together too terribly well beyond the simple relations (triads built upon intervals, etc.) and the book does little in the way of explaining why these concepts are even important at all. Only because of my background in concert music can I mildly appreciate what the book is trying to say, and even that's pushing it.
All in all, avoid this text if possible. Solid 2/5, do not buy.