As far as the battle system goes, being able to switch on the fly to other party members is good, but I hope we'll be able to set AI for the ones we are not controlling. And I don't mean XIII's poor paradigms, but a return of XII's gambits, if nothing else. Preferably with even more gambit options for an even higher degree of customizing the AI.

Not sure how the fight against Safer Sephirot would work in an action-based battle system, though.