I just took GMAT and got total KO'ed!
I thought you might want perspective from somebody who scored lowly on the test so that you don't repeat the mistakes.

640: 39 Quant, 38 Verbal.

I scored 680 and 710 on my practice tests.

To start, I was already stressed with parking situation. I know I should have visited the site a day earlier but...well I didn't and I am to blame for it.

Quant started easy and around Q 4 I felt some challenge. I always did poorly on time management during my practice test, so I took a guess and moved on. Next set of questions all felt too easy. I think around question 33 I realized that I was getting too easy questions. Quants has been my strong point and I just couldn't understand why I wasn't getting tough question. Panic tried to set in but I overcame it.

Verbal started and I just couldn't focus. Around mid way through I completely blacked out. I couldn't understand a sentence that was in the screen. I felt I want to dump the test. I just selected few answers and after 5-6 questions I regained. I then answered the rest.

I am not sure what happened. I took a day off to relax the day before the test. I did study few hours but rest of the day was spent chilled.

I will retake the exam, but I will most likely miss the deadline for 2nd round so might have to wait till year 2013 for my MBA.

I hope you don't go through what I did.