What I loved most about the story, aside from the fact that it was a well done non-Doctor, non-companion POV, was that we got a protagonist who was also the antagonist. Not only did we get that, it showed wonderfully how people have it in them to be very selfish and destructive at the same time that they have it in them to be selfless and heroic.

I admit, I'm also a sucker for a Doctor Who story where he isn't the one who saves the day.