The gameplay is much like any other LMBS (Linear Motion Battle System) of other early "Tales of" games. You attack physically in diffeent way depning on which (if any) directional buttons are held down while you press the attack button - which is important, because they determine whether you slash or stab; which is more effective depends on your weapon. Straight edged weapons do more stab damage that slash damage, and curved edged weapons fo more slash damage than stab damage. There's the Arte System, allowing warriors to use special combat skills at the price of TP (Technical Points), and allowing mages to cast spells, also at the cost of TP.
The enemies are...certainly creative; you will find many enemies that you couldn't even have conceived of.
One thing that bothers me most with this game, is how MUCH there is during battle. Sometimes, there's so much going on on the battlefield that you can't even tell what you're doing. Flashes of light everywhere cover up your character and whatever he or she is doing. Sometimes you won't even know whether it's you hitting an enemy, or an enemy hitting you. This problem is not all present in the simpler battles of the early gameplay - but as you progress and battles become more advanced with multiple enemies, more allies, and the growing skill set of both, battle ends up being blinding.
Another is the puzzles. I'm okay with puzzles, as long they make sense. During the course of the game, you will have to enter the temples of summon spirits, which are heavily guarded by puzzle upon puzzle. They are quite simple during the early stages of the game, but grow completely unintelligible towards the middlepoint of the game.
You will find yourself walking back and forth between switches far away from each other, all the while fighting enemies in between, even though you can't see them for all the flashes going on even in simple combat! It's frustrating.
Tales of Eternia has a great story, great characters, awesome boss fights, but horrendous dungeons with unintelligible puzzles and so much flashiness during normal combat that you can't even see what you're doing.