A guy named Nick Frost played Santa Claus! There are no coincidences! Also Nick did such a great an original job of playing Santa, there were so many ways to read those lines and he picked something that to me was hilarious.
I thought in the short time we saw him he was a really good Doctor (or not a Doctor). And I think the Time War does need to be fleshed out more so I wouldn't be surprised to see him come back. In fact, I'd be down right excited!