My DH and I have flown airtran only for about 3 years now. At first we were a little skeptical of the low-frills approach, but found them to be outstanding!
Their fleet is incredibly new compared to almost all other airlines, making the planes very nice, XM satellite radio on almost all, very clean, etc.
The staff has been superb every time we have flown.
They do change their schedule more frequently than other airlines, but we have found that if you book the earlier flights (as with any airline) the chances become slim to none that they will change, especially to somewhere busy like MCO. Also, just to note, we have NEVER had a change fee if they have changed our flight times (no matter how small or how drastic the change). In fact, 2 out of 3 times that this has happened, we have been able to go to a) a closer airport and/or b) book a cheaper flight and receive a discount. Almost makes us WANT the schedule to change if the price comes down
Boarding, etc are never a problem, and we have literally ALWAYS arrived ahead of schedule.
Your mileage may very, but we are literally almost in tears that we got a Southwest ding! fare that was too good to pass up. We're honestly dreading the change.
Good luck to you!