A couple notes on Uber, Mears has a contract for Disney, Universal, the airport and the convention center. Nobody but Mears is allowed to wait at any of those locations for pickups, you can call other people in and if you see another cab company dropping off someone you are allowed to "hail" them but they can't sit and wait for potential customers. This MAY impact the time it takes for someone to come pick you up if you use Uber, especially if you are doing it from a resort.
The other thing is that all cabs except for Mears must pay parking fees (thus passing it off to you) to enter theme park parking at Disney. This isn't an issue if they are carrying current resort guests, but will be an issue if you aren't a resort guest.
Not trying to scare you away from Uber, just things to be aware of.