I will go ahead and assume that we're talking about the GMATPrep software.1.
I actually saved the two GMATPrep tests
until the end. Although I never felt "extremely defeated" prior to seeing my score, I thought my performance was just okay. I've read about others who felt great about their performance, but were ultimately disappointed by their actual score. And then there are still others who have a good sense of what's going on in terms of their score. As you pointed out, it all depends on the person. 2.
The GMATPrep was very close to my actual score. It's the most realistic and accurate test simulation available for the GMAT. 3.
The test center's notepad is essentially identical to what Manhattan sells. It was a good purchase for me. For more info, see here: manhattan-gmat-test-simulation-booklet-w-dry-erase-marker-94084.html