I did not like it. I had connection flights the first being a SW and the second being a AT.
Because they use two different seating systems I could check in (or in my case early bird check in) like usual on SW but on AirTran it would not let me pick seating until I checked in, the website said at the gate but I was told it would be at the online checkin (early bird) and then it would automatically assign us our AirTran seats.
I did not know this until after I bought that flight. I was traveling with my mom (I paid cash and she used her points) so we had separate confirmations. So we would be assigned as two separate passengers not a 'party of 2'.
She's elderly and not a good flyer so it majorly stressed her out which in turn made me feel awful for buying the stupid tickets in the first place.
So I called to see about changing flights or what could be done. There weren't really any other working flights time wise, so we had to go with the airline 'making a note' that the two confirmations numbers were traveling together and would prefer to sit together as well. There was no guarantee that we would be seated together but it might.
We did get lucky and were seated together. Crappy seats but together.
It also will not let you use resort checkin on
MDE if you have AT and SW as a mixed itinerary.
I refuse to use the AT system until they fully merge and are using the same system.