My cousin and her two DD's went last year, because her DH to visit family outside of the country and she did not want to travel that far with the girls. She took them to WDW instead.
She said never again. It was the most crowded, unpleasant WDW trip she's ever had. She said that they did not even go on a lot of rides because the lines were so long and the FPs were out by mid day. She also said MK closed to capacity several of the days before 10 am.
She did try to make the best of it, and loved the decorations and everything. But she said next time, she's going early in Dec.