Very good episode. I've always loved the standalone adventures more than the arcing ones, and after all the timey-wimey drama last season that didn't really lead to anything, an opener of that kind was refreshing.
But, even so, I'm not terribly convinced this wasn't an arc-y episode. The whole "Doctor Who?" thing last season seemed to be setting up a potentially cringe-worthy Moffat retcon of the Doctor's past, but the conclusion of this episode and the theme of "memory" has me convinced something is amiss. The Doctor seems pretty happy that the Daleks don't remember him, but I have a strong feeling that will be his undoing. So perhaps the answer to the question won't end up being about history, but of lost identity. Maybe what brings about the "fall of the Eleventh" is the fact that even the Doctor has forgotten who he is.
As for Oswin, I'm not entirely convinced she was forthcoming about herself here, or that she's really dead. Reeks of Moffat weirdness. I have a feeling some genius plan of hers is afoot.