I had head mixed reviews about long lines and waiting times, so we planned to get there early. We arrived 5 minutes before official opening, and it wasn't busy at all. Food was fresh, and there were no lines at any truck. Within an hour, it started to get quite busy though (although still not terribly long lines or waits).
The food was a fairly nice selection of various local food trucks. I brought my appetite, and OtG didn't disappoint.
Prices are reasonable. You'll spend a little more than you might going to to a bar, but they didn't serve tiny portions either.
Overall, highly recommended on a Friday evening at Fort Mason Center if you're into trying different things or sampling street-meat.