My shopping list on someone else's wall & why I love Banksy

I thought it was great when i stumbled upon it yesterday, but i only now realized that it's the only item that's been sitting on my shopping list for about 3 weeks now & that i haven't been able to get (time crunch!)
And then another coincidence: a couple of hours later i finally went to see Exit through the giftshop (a much better movie than I expected) & of course it made me think, yet again, about what's the difference between good & bad art.
This milk wall is good to me. And so is Banksy. Simple & unexpected. This is it.
If i only knew how to get the simplicity right....