It's very crowded from what I hear. My cousin & her daughters went Dec 03 for Christmas and said never again. It was pretty , but just too crowded for their tastes.
Try earlier in Dec. Still decorated but less crowds.
I would say by the 20th you would be getting the peak crowds. I have gone quite a number of years in early December, the slowest time of the year, least costly, great weather, all decorated. Enjoy.
Hi, DH and I were there for Dec. 2002 (MVMCP) from 12/12-12/22 and the crowds started after 12/19. Before that it was empty, no lines, the weather was great. (apprx. 60's degree).
We went again in Dec. 2003 (12/15-12/21) and it wasn't crowded until again about 12/17 or so. Then it got pretty crowded! It was freezing cold, (and we're from NYC so their "cold" isn't really cold to us) but it was about 40s at night.
We would still go in Dec. this year, only b/c the decorations are beautiful for Christmas and the crowd isn't as bad as summer crowds. (and the weather is bearable IF you're prepared...unlike us...we ended up buy fleece blankets and gloves!)
We were there this past Christmas from 12/20-12/29. We found the first few days to be very managable and we got way more done than we had expected. Of course, this involved planning, getting to the parks before opening, using EE, and FPs. It worked out very well because by 12/25 things got packed. We still used our strategy and it worked well for the last few things we had to do and some extras, but if we had specific plans of must dos for past the 25th, I dont know if we would have been able to get it all done.
As for weather, our first day was very cold. Seeing life guards in sweat suits was quite funny. That night we had on winter jackets & mittens and we were still cold. However it did warm up some for us, we wore shorts some days and made it in the pool once.
I would do it again, not every year, but its not out of the question.