We did our first Disney Christmas last year.
We arrived at AKL Christmas Day afternoon and left on Sat Jan 3rd. Having read all the threads we expected and were prepared for chaos. NOT SO MY FRIENDS.
We hit EPCOT that evening for our ADR and tought where are the crowds ?? Yes, it was busy, but no busier than over Easter, and certainly not shoulder to shoulder
Dec 26th we hit MK - It was an EMH morning and thanks to poor bus transportation we missed the first 40 minutes. At rope drop we went to Splash + Big Thunder, rode both and Pirates and Space and Buzz before the crowds started to build.
The rest of the week was similar.
The busiest day was New Years Eve (this was shoulder to shoulder) - get to a park early (very early) and stay there all day and night.
Christmas, for us, was a pleasant surprise. The parks were not as busy as we had planned for.