We've only used AirTran once, in Sept. '06 for our Disney trip, flying out of Detroit.
We booked our flight through CAA as a part of our "Free Dining" package in mid May - so that was about 3 and a half months prior to our departure.
If I remember correctly, there was a change made to our departure time, but I think it was only about a one hour difference. I think it changed to a later departure, and we wound up taking off at about 2 pm rather than 1 pm - not a big deal. The change was made to their schedule in early August, well before we got our final documents and stuff from CAA.
In terms of service, AirTran was fine - they are a budget airline, and we expected nothing more than you might get with WestJet. I don't think that they were as "friendly" as WestJet tries to be, but they were nice to us and our kids and did nothing that would warrant a complaint of any sort.
What DID impress us (note here that weather was perfect for both flights) was that takeoff from Detroit and Orlando were both right on schedule, and our arrivals BOTH times were slightly ahead of schedule. I don't know if the pilot was lucky enough to pick up a tail wind or something both times, but we landed about 15 minutes ahead of schedule each way.
I would use them again.
We're hoping to go again (late Aug. '08), and we will likely either use AirTran or Southwest out of Detroit - both the cheapest airlines with direct flights. The two considerations are:
1. AirTran has been added as one of the airlines where you can check-in for your return flight at the resort (they weren't in '06), and Southwest still hasn't made a deal with Disney to do this.
2. Southwest doesn't have the resort check-in, but their deals are often better than AirTran and we might be able to get a cheaper flight. There is a chance we could save a total of $50 to $100 (family of four).
So that's a toss-up. I might be willing to pay the extra $50 for a resort check-in, but if Southwest gives us a DING that saves $100, I'd likely jump at that!