My least favorite meal at a sit down in Epcot was at Tutto Italia. It's just not good Italian food, simple as that.
On the other hand, contrary to the general consensus on this thread, I've never had a bad meal at either San Angel or Coral Reef, especially Coral Reef. I had their trout on white bean salad last time we were there (I think it's still on the menu in some form), and I thought it was fantastic. San Angel is slightly above average, but taking into account the Disney mark-up, I can't really complain about the prices or portion sizes. You pay for the ambiance, there, but the food is nowhere near as poor as I've read described numerous times on here.