We used ME last week. No problems at all, was very satisfied, fly in on a participating airline and you can check in for your return flight at your resort.
For our experence, we got our luggage tags well over a month before our trip, on the day of our arrival we checked in our luggage in Buffalo, NY, when we got to Orlando we went to the ME welcome center (the counter where you check in before you get on your bus, then we were directed to the line to stand in for the bus going to the Pop Century we waited about 20 minutes, it would have been less time but they were waiting for a bus that a girl in a wheel chair could accomodate, I did not mind the wait, it was nice to see how assisting the CMs there were for her and her family. We got on the bus, got delivered to the Pop, checked in went to Epcot, Ohana for Dinner and saw Wishes at MK and when we got back to our room that night our bags were there.
Then the day before our departure there was an envelope on our door with instructions and a reminder about ME for the next day. Since we were not on a participating airline we put our luggage on the bus.