Like other commenters, we have been underwhelmed as well. The most interesting thing offered is the addition of truffle salt to popcorn - not exactly revolutionary. The rest of the food is about 20% overpriced and 100% unremarkable. We'll continue bringing our own picnic food to Lake Harriet for our weekly picnics there.
Edit: also, "the best thing that ever happened in a public park," really? Because it isn't even the best food in a public park within a 1 mile radius - that would be Tin Fish. Or the best food in any Minneapolis park - that would be Sea Salt in our home park at Minnehaha Falls. And I would venture that the best thing that ever happened at Lake Harriet was the building of the bandshell.