Gotta agree, The Girl Who Waited has become, along with The Doctor's Wife, one of my favorite episodes of the entire series. All the Series 6 naysayers can go eat a shoe!
My one criticism - WHO THE HELL WOULD PRESS THE RED BUTTON?! Green = good, red = bad, so when you have the option why would you choose red?!
And damn, I was never one to criticize Karen Gillan's acting ability outright, but I was never particularly impressed by any of her performances. But with this episode, she really showcased her considerable talents. I hope that, once she's done with Who, she gets all sorts of work and doesn't fall victim to typecasting.
Oh, and Arthur Darvill was amazing, too, but he's been the one who has impressed me time and again these past two series, so that didn't particularly surprise me.