my family takes airtran from atl to nyc quite often as they have some of the cheapest tickets. other than the fact that airtran was once called the "easyjet' or "valuejet" that had a string of accidents (florida everglades - most famous one). they changed their name after that and seem to have prospers without a hitch since then.
as for quality - you get what you paid for. it flies you from point A to B without the creature comforts we'll accustomed to.
Flew Air Tran Fort Myers to White Plains. No better or worse than anyone else these days. Plane was not full on the way up. Had an extra seat between us. On return were able to upgrade for I think $60 each to Business Class. Enjoyed it. If we go up in January I would use them again.
"Change Fees Based on the fare rules, you may have to pay a service fee and/or a difference in fare. For travel within the 50 United States, the fee is $150 for Delta flights.
For travel outside the United States, the change fee is typically $250, but can vary based on location and type of fare. Changes are usually permitted only to the return portion of an international itinerary."