The original reveal confirmed Final Fantasy IV's Kain and Final Fantasy XIII's Lightning as playable characters. The game will also add "new game modes, story missions, items, alternate costumes and combat features" as well as a playable Chaos storyline.
There is also an "assist feature that enables players to enlist characters as back-up in combat," which should help feature more of the cast. I felt that I focused on just a few characters in the original game, but this assist feature should be a welcome addition.
There's no word on whether this will also get a digital release. PSP Go owners--myself included--were left out in the cold with the release of Kingdom Hearts: Birth by Sleep, which was not released digitally. Shacknews has asked Square-Enix if Dissidia Duodecim will get a digital copy.