Air Tran is a good airline. My in-flight experience with them has always been wonderful. No problems with traveling or flying.
The only point of contention that I have with them is from my home airport (PWM) they seem to change their flight schedules quite frequently especially if you book far in advance. In fact I can honestly say that I have never booked a flight with them where they haven't changed the time - sometimes by a few minutes, other times by hours, and still yet they have cancelled a direct flight with nothing to replace it with.
Now, all airlines do change flight times around but in my personal experience, to the places that I fly, Air Tran has a much high track record of doing this than other airlines. If my travel times matter I usually choose a different airline or wait to book until I am less than 90 days out. If my travel times are flexible then I never hesitate about booking Air Tran.
My teenagers fly on Air Tran all the time. They love it and have never had a problem. But they are usually flexible with the changing flight times when they travel -- i.e. they usually need to be somewhere on a specific day not necessarily at a specific time.