I have it on the GC, and I've found that the difficulty is just right. I died a lot, but it's one of those games where you get a little better each time you play it, and (for the most part), you can see where you messed up when you died.
I personally found the default difficulty (Kids) to actually be too easy, as I blew through the first three levels on the first sitting. I started over on Adults, and found it to be just right. There was a lot of dying involved, but it was a lot more satisfying to play.
My main beef with the game is that in order to really play the game "correctly", you've got to somewhat play defensively. This isn't like DMC where you can take the fight to the enemy and get rewarded for it. In practically every fight of the game, your best bet is to stand in front of an enemy, wait for them to attack, dodge the attack, THEN start your attack once they're dizzy/confused/etc.
Still a great game, though, and quite replayable.
