The battle system is sort of awesome.
RPGs always need a good battle system, and Opoona's is already surprisingly deep, yet simple to control and understand, all while having fights not take a lot of time or have a lot of overhead. Most of the battles I've been in during the beginning of the game seem to take just 15 seconds, yet crammed in that 15 seconds is a load of tactical decisions. It's the first RPG battle system I've seen to quickly and intuitively incorporate actual 3D spatial thinking into the gameplay. It's really quite genius.
I'm just in the beginning of the game, but basically you do all your fighting with your "bon-bon" (your energy ball basically). You don't attack by pressing a button, but by pulling the analog stick in one direction, holding it for a long or short period of time, and releasing it. This sends your attack flying in any of four different arcs depending on which direction you held the analog stick in, and the attack will be strong or weak, fly quickly or slowly depending on how long you charged it up. Since the game is real time, the time you spend charging up an attack, and the resulting speed of the attack, are critical factors in landing attacks before enemies land theirs. Since you need to recharge to 100% readiness (energy) before attacking again, charging up too much can leave long stretches where you can't attack again and thus are somewhat open. But don't charge up long enough, and your energy ball will fly so slowly that you'll lose too much anyways.
Once again, I'm amazed at how this game came up with such a simple battle mechanic, one that's easy to control yet incorporates so many factors. For instance, enemies are situated at different distances, so sending a slow attack to an enemy far away will seem wasteful whereas an enemy right in front of you might not require a really fast-moving attack since the time-savings are negligible for him. And since enemies are situated in 3D space, the arc of your attack(forward, arcing in from above, curving from the left or right) can actually result in your attack hitting another enemy instead of your chosen target. Well-timed attacks can even interrupt enemies moving in to make their attacks, making handling your timing, and thus attack strength and speed, all integral.
I've only just started the game and already I've been in fights with as many as 10 enemies and had to strategize accordingly (which enemies do the most damage? Which can I take down in one hit? Do I spam slow attacks that recharge quickly, or charge up for strong attacks after which I can't attack for awhile?). These such attacks go down in such a furious flurry of action that even though they may last less than 30 seconds, they feel like they contain an immense amount of activity. Some enemies also exhibit characteristics which defend them from certain attack directions, meaning if I attack from the sides, they have armor that reduces damage. Some are floating, so I suspect that attacking with the overhead lob has a greater probability of hitting them.
And this is only with one character, with two special abilities/magic/forces, and limited items. I had a blast, and am now enamored with the battle system.