I've been taking my DD's since they were 2 1/2 and 4 and they love it. It is a wonderful bang for the buck so to speak because the kiddie area has no lines and the kids play for hours straight (no lines!!). Ketchakiddie Creek (the toddler area) has a ton of stuff for the little ones.
We usually get lunch and then go for another 11/2 -2 hours so we are out of the park somewhere around 2-3.
Because it is non stop outdoor playing, they get pretty tired pretty quick and have always slept on the bus back to the resort.
Have a great trip!!