Every child is different, and although "2's" are commomly referred to as "terrible" in many different situations, I think it's important to keep in mind a vacation may be more stressful for a child old enough to be aware of his surroundings, but not quite able to grasp the idea of vacationing.
They've been taken away from their home, bed, toys, routine, etc., and for some children, at some ages, it's natural to cling to something that offers them comfort or to even try to control the situation by their behavior.
Also remember... Disney is sensory over-load.
If possible... take a few over-nighters or try a mini vacation, just a night or 2, to reassure him by getting him used to the idea of "being away and then returning home," before your Dec. Disney stay.
Talk to him about vacation, look at your photos or video and watch the Disney planning DVD.
Also, if you didn't bring your own stroller on this last trip... try bringing his from home, to give him his own familiar space.