As far as I know they do not do airport to resort transportation. We always take a towncar from MCO to Uni and towncar to Disney for the second half of the trip.
I love the transportation by boat to the parks/City Walk. It is a hub. You go to the dock, board boat it drops you to a central hub and you can either go to City Walk, mini golf, or either park. It reminds me of Disneyland, you don't waste a lot of time getting to the parks and if you hop it is mere minutes or you can easily pop out of the parks go back to your resort swim and be back at the parks or City Walk for a meal.
The map is the best I can find but Uni uses their waterways to transport guests from the resorts to the parks. The back up for severe weather is buses but I've never been on one of their buses. We stay at the Portofino (bottom right) board the boat, sometimes add guests at Hard Rock in off hours and then it dumps you off at the parks and or City Walk.