We used it Feb. 9th from Wilderness Lodge. We used Magical Express and loved it. The day before we left they told us to be on the 7:05am bus and that we could check in our bags an hour before that. It was great! We didn't have to carry our luggage and our boarding passes were in hand. I thought it went very smooth.
Just to clarify.
Magical Express is the service where they drive you to or from the airport on the Disney Bus
Resort Airline Check-In is the service where you can check your bags and get your boarding pass at your resort.
Most of the time people use both when available. But, if your airline does not support RAC or for some reason you choose not to avail yourself of it, you can still use the DME to get a ride to the airport and then check your luggage and get your boarding passes there.
Here are "the rules"
Comming from the airport
You can take the DME bus and use the luggage transfer service where Disney gets your luggage and brings it to your room
You can take the DME bus, and bring your luggage along with you.
You CANNOT have Disney take your luggage while you take transportation other than the DME bus
On your return
You can check your luggage and get a boarding pass at the resort, and then take the DME bus to the airport
You can take the DME bus without checking your luggage at the resort.
You can check your luggage at the resort and take alternate transportation to the airport.
Whew !
And the service, in my opinion, works wonderfully
-dave