The combat system is time based. During combat, at the top of the screen there is a timeline showing all characters; the initial positions are based on the character initiative and whether it was a surprise attack. The characters' speed is reflected in how fast their icon moves along the timeline; when a character gets to the end, they have their turn.
For the turn, you can fairly quickly attack the nearest or a selected opponent, or you can defend yourself, move, cast a spell or use a potion or special move (IIRC). The action is paused when the interface comes up to make a selection, but combat moves faster than most turn based systems.
I played Grandia II on PC, and a gamepad makes the combat interface quite easy and fast to control.
The game itself is pretty linear, but does have a fairly good storyline.