I've frequented these boards for months, but finally registered for an account so I could post my experience with the online version of the GMAT.
A bit of background: I wrote the GMAT just over five years ago when I was planning to do an MBA and scored 740 with little to no study (I have a strong math background and am a native English speaker). Unfortunately, life got in the way, plans changed, and I was forced to indefinitely postpone my pursuit of graduate studies.
Now: After dedicating approximately 200 hours to studying, using a combination of the OG,
Manhattan Prep books, and online forums, I was regularly scoring 750+ on timed practice exams, and feeling fairly confident going into exam day. That confidence fell apart within minutes into the exam.
The whiteboard tool was a nightmare to use. Beyond the normal difficulty of doing math on a virtual whiteboard, It constantly froze and was difficult to navigate. Between that and having to flick back and forth between screens, I would estimate that for me, it added an extra 20-seconds per question - an extra 10 minutes that I just did not have. Suffice it to say, this resulted in a lot of 'guessing' on the exam, particularly at the end in a rapid attempt to simply complete it. Combine that with the fact that you cannot wear earplugs in an uncontrolled environment, and well, it was an absolute disaster.
My score - 550... a far cry from my old 740 and the multiple 750+ practice exams prior to test day. This was a disaster and a poor excuse as an assessment of ability.
I am sorry to hear about your bad experience. Did you practice on the whiteboard before giving the exam? Did you cancel your score?