My kids loved it! We went for an early dinner (5ish) in December 2014 (they were 5 and 8 at the time), and were seated when there were plenty of empty tables. We went immediately to the buffet and filled up plates.
I liked the little metal bowls with beef short ribs sitting in some kind of grit (didn't eat much of that part). The meat was delicious. I also ate a few things from the salad bar, and maybe tried a couple of other things. I had 2 partially filled plates, to make sure there was room for dessert, kids ate one plate only (the usual chicken nuggets type of fare, and I throw on some broccoli to make myself feel better, lol). The food had just been put out so it seemed fresh(ish). My kids were in heaven meeting the characters. They also loved the dessert table-mostly the soft serve ice cream.
I do think, as with all buffets, that going early is key. By the time we were leaving, it was very crowded. That being said, I would never go to Chef Mickey's (or any other character meal) "just for the food". You are paying for the experience and the chance to stuff your face if you are so inclined. I feel similarly about the other character meals we have done (Akershus, Crystal Palace, CRT, Garden Grill, Cape May breakfast)