We LOVED it. My kids were 3 & 7. They loved both the quiet pool and SAB. They loved the boardwalk. The loved the "big tub". My 3 year old was just amazed that he "slept in the kitchen" on the sofabed. We loved walking into Epcot in the early evening after naptime/rest.
You'll probably want to bring a double stroller if you have one (or at least a single if you don't) - while it may be easier to sometimes rent one, it is wonderful to push the kids home from Epcot or even MGM if you're up for the walk.