You'll find new ways to control Paradigms, instant changes and, unfortunately, quick time events.
'Final Fantasy XIII-2' is bringing a few very exciting changes with it. It's not going to completely change up the game like 'Final Fantasy X-2' did, but you'll find some tweaks here and there that shake things up a bit.
The newest trailer shows off enhancements to the already streamlined battle system which should add a bit more depth for players that crave it. You'll be able to change the party leader mid battle, which is a nice touch, but the most interesting bit is Paradigm Tune, which allows you to set up behaviors for characters before battles. It's a bit like the Gambit system from 'FF XII' but quite a bit simpler.
Not all changes are good changes though. The trailer ends with a look at what Square Enix is calling "Cinematic Action" but you'll know it better as the much lamented Quick-Time Event.