We went for lunch because the only food that gets good reviews are the burgers. For some reason, I am more of a cheeseburger/fry person at lunch. They do have dinner type food on the menu, but most people on these boards say to stay away from it. We only got cheeseburgers so I can't give you first hand knowledge. It is a dark and cool restaurant so a great break from the sun.
As far as only staying half a day, we love MGM and easily stay a whole day. Even if you leave, come back for Fantasmic!