Disney's Magical Express (DME) is free to all onsite resort guests. You'll need to make an advance reservation - for
DVC members, just do this thru MS- others can all the DME number. They will want your airline and flight info and will send out luggage tags in advance. With these tags, the bags will be sorted before being put on the bag carousel- so make sure you have everything you'll need for the next couple of hours with you. If the tags don't come in time, you can still use the service, but will have to personally collect your bags. Regardless of your airline, you may use this service.
The bus ride is pretty efficient and any carry-ons may be stored under the bus. There are usually no more than 4 resorts represented on each bus- so the trip is quick with no more than 3 stops before you'll be off. The checked bags will arrive separately - usually within a couple of hours of your arrival. They will be delivered to your room.
For the return trip, guests using Delta, Song (and a few more I can't recall at the moment) may leave their bags at the DME desk at your resort and they will be taken to the airport- you won't need to mess with them until you reach your final destination where you'll pick them up at the airport carousel. Guests using other airlines may still use the service, but will have to handle their own luggage- it will be stored on the same bus you ride back to the airport. The bus usually comes about 3 hours prior to your departure time- to allow enouhg time to get to MCO and clear security with plenty of time.
Even if you change resorts during your stay, DME is still available from all WDW onsite resorts without cost.
We have used DME twice so far and found it well run and efficient.
Enjoy!