I don't think I'd really compare the battle system to Grandia, honestly. It's more like a mini-tactical battle system with elements from Xenosaga Episode I -- specifically, the turn bonuses and the ability to boost yourself into the turn order list. (For those heathens who hated Xenosaga, note that these are both elements that virtually everyone LIKED about the first game!)
And the magic system bears more than a passing resemblance to the Materia system from FF7.
In general, it's like a mish-mash of successful battle systems from other games, which means it's lots of fun and will feel right at home to anyone who grew up on RPGs in the PS1 and PS2 eras. The biggest issue with it is that battles are slow, as previously noted -- but they're also few and far between (and avoidable, since you can see enemies on the map and run around them if you choose), with the majority of Trails taking place in towns and cutscenes. Story definitely trumps gameplay in the series, by leaps and bounds, so asking if the battles are good is kind of asking the wrong question with this title. They are, but you'll be spending such a small percentage of your time actually fighting things, it almost doesn't matter!
This is definitely a game for fans of story-driven narratives above all else.
-Tom
