I had my doubts about this episode before it was shown and the trailers didn't help. The opportunity to make the whole thing a huge CGI whizz-bang battle knee-deep in daleks would be hard to resist: after all many people like that kind of thing. Instead, they took a completely different path. Not as great as story as the wonderful psychotic John Simm master who made you sympathise with him despite everything, but still one of the best. I'm not sure how they square the final minutes with the apparent age of doctors when they regenerate, but even so it was a nice little extra