I beat the game proper and mastered all the job classes available (all but 1, the Necromancer). However, the optional dungeon's encounter rate is WAY too goddamn high, the enemies are cheapasses (Behemoths that cast Meteor upon dying, for example), and most don't offer any experience, just job points. Which are useless to me right now since I mastered every job with every character except the Necromancer... which I can't even get until I finish this evil, evil optional dungeon.
That said, I was shocked how much more enjoyable the game is when the battles are faster and the translation doesn't suck. "Knights do it 2-handed" is a phrase that will forever be scorched into my memory.