I personally think there is something at WDW for people of all ages 0-???????????????.
My son was just 18 months when we went for the first time. He had a blast. Will he remember any of it when he gets older?? Probably not... But I don't care if he remembers or not. He had fun, and he was "living the moment". Plus it makes for some super cute pictures. My daughter was 4 when we first took her and she loved it (Jan 06). SHE HAD A BLAST!!! :sohappy: :sohappy: :sohappy: We took our digital camcorder and I made a movie out of our recordings. The kids love that a lot.
Anyways, the whole thing depends upon you and your child. Take into consideration crowds, heat (depending on when you go), long lines, the traveling, lugging stuff around, nap times/breaks, etc... but honestly for us, it was 100%percent worth it. In fact we are headed back in a few months for 17 days.