From what I understood from the SFO AAngels, it's not necessarily the checkin system, but that the old DOS-style text command SABRE interface has been finally (after months of delays) switched over to a graphical UI system. Point-and-click.

AAngels have been given a fat 3inch manual binder, but I doubt they will get used to it that quickly. Apparently some/many of the "tricks" and workarounds they have learned through the years with the text-command system are now hard/impossible to do.