At first, I thought the RoF demo was just okay, but after I got a hang of it, I enjoyed it. You select your target and the direction you want to go. While running to your destination, you can either jump and shoot or just shoot while running. You can also do combo/team attacks if your members are set up in a triangular position.
Zephyr is just plain awesome. He's the guy you want to use if you want to take out the enemies quickly, especially during those team attacks. I like that there's some nice little strategy involved. There was one piece of music that I enjoyed; not sure if it was the boss battle or when one of my characters was dying. It really pumped me up.
My only concern is that the game might end up being bland after a while. As long they keep the battles fresh throughout the game with new weapons, environments, enemy placement, etc, then it could end up being a great game. Take Valkyria Chronicles for example. It did a fantastic job on making pretty much every battle different. I can see RoFs battle system's novelty wear off fairly quick if they don't do that.
I may end up buying the game if I don't hear any complaints about the battle system or the game getting bland after a while because of the things I've mentioned.