Wow, what a first experience! That was definitely a glitch and very unusual. I go to WDW at least 4-5 times a year and have used DME every trip, since they started it. In fact, I used it the very first week it was in existence. Yeah, I was one of the original guinea pigs.

So far, knock on wood, I have never had a problem with them. I'll be using them again for my Nov 26th-Dec 4th, Feb 4th-11th, and May 5th-13th trips. I've used them over 25 times without a problem and hope I haven't just jinxed myself.
Now I did have a problem once going back to the airport, but it was not DME's fault. Just as we were loading, a large family came running up demanding to be put on our bus, as they had got tied up in DTD and missed their bus. The driver and finally the guy with the clip board explained that our bus would be full and there wasn't room for them on the bus. The dad started yelling, demanding that since our flights left after theirs, that some of us be put off the bus to wait for the next bus, or else they were going to miss their flight. It came out in the course of the dad's frantic yelling that they had intentionally missed their pick up time because they thought the three hour before their flight time was ridiculous and they just thought they'd hop on a later bus. They then got tied up in DTD, leaving DTD later than they planned, then the bus from DTD was late, and everything together made them later than they'd planned and they absolutely must get on our bus or they were going to miss their flight, so some of us
had to give up our seats to them and catch the next bus. When both the driver and the guy with the clipboard again explained that wasn't happening and since they intentionally missed their assigned bus, Disney was not even technically responsible for getting them on another bus. The guy then climbed onto the bus, motioning for his family to follow him and said they'd just stand then. He was told that wasn't happening either, but then he refused to get off the bus and we couldn't leave. A manager type came out and finally talked him off the bus and when we left, was walking the family inside with the dad screaming at him that they'd better not miss their flight. Then we got tied up in a big wreck on the way to the airport. We weren't in the wreck, just slightly delayed with the traffic from it, then we were the second stop at the airport. Then security at MCO was ridiculously long--much longer than usual. We made it to our gate, but didn't have alot of time to spare. With any one of the delays, we would have still had plenty of time, but with all the delays piling up, we were cutting it shorter than I like.