We took our 26-month old son (and his older sisters) over New Year this past year. Before booking the trip, I was firmly in the camp that he was too young to get anything out of it. Was I wrong. Although he undoubtedly won't remember it when he is older, it was well worth it to see the amazement on his face every time he encountered something new (which was just about at every turn). We played for over an hour-and-a-half in the garden area by Mary Poppins at the Grand Floridian, and we must have rode the monorail a dozen times! He absolutely loved the trip. He still watches out for the pirates he saw on Pirates of the Carribean.
In sum, I would absolutely not worry about whether your daughter is too young. The joy you will get out of watching her will be one of the most memorable parts of your trip.
Have fun!