I guess I'm the exception, which is surprising, because I'm normally very easy to please.
I had to take Air Tran on my last trip back to Md (contract carrier changed), and I wasn't thrilled. The planes were REALLY cramped. I'm a size 6, 5'4" person, so I have never had problems, but I was jammed in this time. We went in (and out) of the oldest, un-refurbished terminal at BWI, and it was really nasty (probably not AirTrans' fault, but it was really icky). The return flight, the plane was delayed at least an hour and they gave us NO notice of when it would get there. They didn't even acknowledge it was late until the departure time had come and gone. Given the icky terminal, I would have gone to a different one to get something to eat if I had know I had a full hour. As it was, the only food there had HUGE lines, so I went hungry.
Now on the good side, their crew seemed very friendly. They were more personable, and less "bored" than standard. Kind of similar to SW, but in a more urban way? (Most SW attendant's I've had have been from the south or southwest areas, so there people come off more like a southern belle, whereas these people were definitely city, but nice). They also offer free earphones (the cheap plastic ones, but FREE), and XM radio.
JMHO, but that's what you asked for.