This is possibly the best RPG ever, if not the best DS game so far.
The story is incredibly interesting and surprises you all the time, the soundtrack is excellent and the game looks great.
My favourite part of the game is the fact that the battles aren't random, you can see the enemies on screen and when you do fight them you fight them on the same screen instead of a special arena, also the real time battle system works well and is much better than the turn based fighting of most RPGs.
With plenty of side quests, multiple endings, secret dungeons, item and enemy lists and the arena mode you'll be playing this game for a long time after you've completed it once.