I went into Dissidia basically expecting Ehrgeiz 2, but what I got was something more akin to a reskinned Virtual-On. With the camera locked behind my character's back, I flitted around a glowy, abstract environment, locking onto my opponent and throwing crazy energy attacks. The game moved quick and the graphics were sharp, which is all well and good, but if I didn't know going in that this was a fight between the Onion Knight from Final Fantasy III and Tidus from Final Fantasy X, I'm not sure how apparent the Final Fantasy connection would've been.
Beyond the basic format, there are some weird mechanics going on in Dissidia. Each fighter has a tally of “brave points” that seem to act as a damage amplifier. The more brave points you have, the more hurt you dish out. And one of your attacks doesn't actually damage your opponent at all; it merely steals some of his brave points, making you that much stronger. (It seems like the other guy can steal those points back, though.) Once you've got a big mess of brave points, you can lay on the damage with your actual attack button to remove hit points en masse.
Another match type featured a little glowing bell hidden somewhere in the rather sizable arena, and once you grabbed that, you could engage a special attack mode that lets you lay on a canned attack animation that's specific to the character you're using. Squall's attack was similar to one of his limit breaks from Final Fantasy VIII, where he launches his enemy up in the air and slashes him about a billion times. There was a little rhythm game sort of thing that preceded this animation where I had to hit a button in time with a moving meter. The number of slashes was equivalent to the number of successfully timed presses.
Based on my brief time with Dissidia, I'm not sure that Square Enix has cracked the code on how to make a successful, non-RPG Final Fantasy game yet, though they should still get a certain amount of credit for continuing to try.