My husband and I ate at the Fountain for dinner on a Monday night in April. I'd say we arrived between 5:30 and 6:00 with no ADR. (We were just sitting at home; DH was like, "I want a good burger. Don't people on your boards say that the Fountain is good? We should go.")
There was no wait and probably 3/4 of the tables were full. The service was good and prompt. I really liked the milkshake that I had, and the burgers were good as well. They are NOT the same burgers served elsewhere at Disney - definitely big and juicy. There was a good selection of specialty burgers, which pleased DH. I seem to remember the fries being really good, too, but I'm not sure.
They also had a bakery case and some of the desserts looked really good, but I had already had a milkshake.

Anyway, next time we want burgers, I would definitely go back.
OH! And I thought they had good vegetarian selections. I don't remember what, but I remember there being a few options. (My sister is a vegan so I always glance at menus for vegetarian/vegan options.)