The Official Guide for GMAT Review, 11th Edition,   ISBN:B002BWQ4JG

Customer Rating: 

I think that the Official Guide is a faily good book to start studying for the exam, specially for the verbal section which is better in general than other books like Kaplan for example.

Customer Rating: 

The book did not come for over a month and when it did arrive it was ripped and torn

Customer Rating: 

The Official Guide for GMAT Review, 12th Edition

I like the book and have received it by the time, and in excellent conditions

Customer Rating: 

I've gone through about 200 questions so far. The answer explanations are excellent for math and good for verbal. Sentence correction explanations could use more detail and I found an error, but sentence correction may be the hardest part to thoroughly explain in a book. I haven't attempted the GMAT exam yet, so I can't comment on how well it prepared me.

Customer Rating: 

I recently took my GMAT (first and only one) and had a score which exceeded my expectation. I purchased this book and the Kaplan guide. Between these two, we have a pretty good coverage. I used Kaplan for test strategy and this OG for actual problems. One thing I found useful was I would take 10-20 problems at a time and timed myself to see if I can average under 90 secs per problem. It's been 20 years since I finished high school (ha it's been that long!) so I rented a math review book from local library and it was a good refresh but Kaplan book also has a decent review section. Having said that it would help if you had a strong education background in math.
Regarding the sample computer tests (two of them) that you get from [...], as the other reviewer said, please do not waste them. My two scores were 20 points apart and my actual score was right in the middle!
Finally on AWA, if you care, there are some templates out there on some web sites and this is a good starting point, you don't have to copy it exactly but it will give you a good idea on how to structure your essays.
Now that I am done, I have to figure out how to get rid of these books :-)