If VVVVVV has one unfortunate barrier beyond the old-school difficulty, it's the price. At $15 USD, some may balk at the two hours worth of gameplay that a single playthrough will warrant. While there's plenty to see and do after blazing through the game's core campaign, the steeper than expected asking price will probably turn some off. (But surely you've paid $60 for an eight hour game, right?)
But for the gamer who has had his or her sensibilities offended by, say Mega Man 10's "easy mode," VVVVVV is for them.