My criterion (which is no more valid than anyone's) is that it's art if it elicits emotion. This clearly does. I'm fairly confident that this has already intellectually/emotionally stimulated the human race more than, say, some stodgy Renaissance portrait of some figure of minor royalty.

As for the people complaining about this being a waste of money, please, give it a rest. I assume you don't have cable TV, or a car, and live like Gandhi, if you feel you have the right to complain about how this guy spends his money.