It would be a great time to go! The parks won't be that busy and bar some possible rides being down for maintenance or rehab (which you can never predict albeit it something springs to mind about Phantom Manor being down for sometime at the beginning of Dec....). The parade will be on, Fantillusion will be on...go for it! It will be cool, but not freezing cold like it was for my visit over New Year - you will need a good coat and pair of gloves though!!