If you know what you're getting yourself into before you go to Game N'At, you'll have a great time.
We went on a Saturday night around 9PM for a friend's 30th (yup, 30) birthday party. We didn't do a party package or anything, but we did BYOB. It's nice that they keep your beer cold in a cooler at the front desk.
Yes, a few of the games were broken, and a few did cost more to play. However, we were having a great time with the free pool, basketball, and pinball that it didn't bother me at all. Go check it out, get drunk for cheap, then hit up the crazy Southside bars.