I've done Le Cellier 3 times over the past two trips (2011 / 2012). In 2011, they knocked it out of the park, both visits. In 2012, it was good, but not as good. I did a "Dine with an Imagineer" lunch at Brown Derby that also had a mushroom risotto filet that was amazing. And at both venues, the creme brulee wasn't very tasty.
The Chocolate Moose was fantastic as always though.
My least favorite place to eat is any place that serves breakfast, with the exception of Tusker House.
I've done Chef Mickey, 1900 Park Fare and the resort breakfasts many times, and they were always mediocre at best (this past 2012 trip 1900 Park Fare was just terrible, I won't be going back anytime soon).
Outside of breakfast, I think that the food overall at Disney is pretty good, and while I have places I care not to visit, I haven't ever been severely disappointed...well, outside of Germany's TS option. I love the venue, hate the food, but I grew up in Germany, so their cafeteria style versions of food really don't sit right with me. I can cook better at home.