The Lodger
It's been pointed out that one of the few genres Doctor Who hasn't really turned its hand to in the past is the blokey flat-mate sitcom. So, in one respect, this episode was trying something genuinely new and, what is more, something which you would expect to play to Moffat's strengths - except, of course, that he didn't write it.
( Rather briefer thoughts than usual under the cut )
( Rather briefer thoughts than usual under the cut )