The food trucks at ESPN are life savers! The quesadillas at the mexican truck down in the grass by arena south were awesome. I think I had 3 over the course of the weekend. Everyone I know that ate other things there raved about it as well. The burger truck (don't know names, it was next to the mexican truck) also had great cheeseburgers. The pizza at the big glass truck is also pretty decent.
The concession food at ESPN is just that, concession food. Nasty burgers, hot dogs, chicken fingers, fries, etc.
Jostens has an ESPN restaurant, but that usually stays pretty packed. It's a sit down restaurant. The line moves fairly quick from what I can tell, but I've never eaten there during a cheer competition, just once for a baseball game.
The "box lunch" a couple of years ago, was a generic bland turkey/cheese or ham/cheese sandwhich. If you choose PB&J it's a grape uncrustable. A bag of plain chips and a drink. Maybe a cookie? I can't remember. I didn't care for it at all, but I also didn't have to leave my seat, a team mom brought it to me, so I can't complain too much!