I would stick with Princeton Review, Official Guide and GMATPrep. Much better all the way around.

[quote="analytchem"]I hear this book, Nova's GMAT Prep Course, is great. It has good reviews on amazon, what concerns me is that they say there are a lot of errors in the math section. They also say the math section is really good though. They also say the sentence correction sucks, which is ok I can use other sources. Is this book worth buying? I know both Kaplan and Princeton Review aren't the best, is this one better?[/quote]

I discovered this book about 3 weeks before my test day. It is good. There are some flaws. There are some plain mistakes in the math. But, it's discussion on formal logic is helpful. Also, its take on the reading comp is very good.

It is not chock full of gmat type questions, but rather exercises that get you used tot he type of questions. It is well above the Princeton review and Kaplan in terms of strategy, but falls short of MGMAT. Consider this book a master's in accounting, the PR/Kaplan a bachelor's and the MGMAT an MBA.

It's not a great book by itself, but as a supplement, it's fantastic.