I'm not sure if this is a popular opinion...but I really liked last season's The Lodger. Granted, it may have been a little too sitcom for some, but it provided a well-needed perspective on the Doctor's behavior by placing him in an all-too-human situation: getting along with a roommate.
Closing Time serves a multitude of purposes - it serves as a companion piece to The Lodger, with a follow up on Craig and Sophie (and their new baby, Stormageddon the Dark Lord of All); an emotional wrap-up that ties directly into The Impossible Astronaut, and quite frankly, an emotional piece that has some really moving, straight-to-the-gut moments that can't help but move you.
In other words, it's the kind of script Russell T. Davies used to write - a heady mixture of the fantastic with a strong emotional core.
Actually, that's not fair to Gareth Roberts....but in many ways, this script is a lot like Turn Left in that it looks at how the Doctor has impacted humanity...but it does so through the eyes on one particular human. While the Doctor is on his "farewell tour", he decides to visit his other, unofficial companion (and there's a slight RTD-ish playfulness about their relationship). Granted, the overall threat is kind of an obvious, not very complicated story....but Closing Time is about much more than an invasion.
It's about facing adult responsibilities....about looking towards the future....about anticipating the end. We get the obligatory last-ten-minutes-explaining-the-arc moment, but this isn't about big battles in time and space.
It's about a man facing fatherhood and gaining the strength to face it fully, as well as another man facing his immanent end and saying "goodbye".
The geekerati may dislike this episode (I don't read reviews until after I've blogged - that way, I'm not letting outside opinions influence me), but I loved this episode.
And I'm not ashamed to admit that.