And here's a TL;DR version of the game play for people who don't want to bother going to that link/reading the article:
Dissidia is an action-based fighting game mixed with RPG elements. The battles in Dissidia are divided into stages, each taking place on its own checkerboard-like map. Characters will be moved around like pawns on the board, able to pick up equipment and potions on the map and fight whenever they stop adjacent to an enemy pawn.
I just hope it looks good, considering the wildly different artistic styles present between installments in the series. I've seen the most recent incarnation of Chaos, and I honestly like the Dawn of Souls version better. But I'm sure he will look different in-game than his official artwork.
I'm also hoping they don't overkill it with Final Fantasy VII stuff. That game is way overrated, I'd like for them to keep it about even for each of the games represented. Though it'd make sense for them to heavily include FFVII, considering all the expansion that game has gotten.