We went on 1/6 for breakfast. We liked it a lot. We found that the characters were more laid back than Garden Grill on our arrival night (GG's were aggressively touchy-feely, like being welcomed by your gregarious family after returning from college. Probably my "fault" for having it noted on the reservation that it was our arrival night and my guests' first trip to WDW, lol)
We didn't like the food as much as Boma's breakfast buffet, but that was a pretty tough act to follow. We still liked the food and found it better than the typical buffet breakfast. Our server was very attentive and lots of fun. I loved the restaurant design, as well. It handles the traffic very well. We all also commented on how well run the restaurant was (my friend has a restaurant background and I have a hotel background,) with a very visible and attentive manager that kept track of everything at once. We even saw him giving instructions to Mickey--that's something that I really enjoyed seeing and that I'll probably never forget.
If you can't make it to Chef Mickey's on your arrival night, we absolutely loved the Garden Grill. They took fabulous care of us, and the characters came to us several times throughout the meal. My guests said that the adult items were really good, and even though I ordered the child's plate for myself I thought it was pretty good too. We literally just parked, ran into Epcot, rode the Universe of Energy (it was closing for refurb that night and we literally caught the last show,) and headed over to the Garden Grill. Except for putting in our tickets at the gate, it was no more trouble than going to a resort for dinner. My poor friend had been up for over 24 hours straight, and she said that she was glad she went and it was a great way to start the trip.