There is a Mears shuttle with regularly scheduled stops at the resorts. We have taken it several times. It is always on time in the morning...coming back in the evening, we've usually had to wait a little, but not an unreasonable amount of time. It sure beats driving! We never rent a car, just rely on Disney transit around WDW, Mears to go to Universal, and Happy Limo to head back and forth to the airport.
Barb