I mean, the two parter was good, Vampires in Venice was classic, but even a broken watch and so on. Third time's the charm, and Doctor Who managed to hit the mark again. Sure, the premise of the episode is almost mandatory for every sci-fi show out there, but the writing was superb, funny, self referential and very well paced and the cast was just brilliant.
From a purely mechanical perspective, the episode was filler. It's meant to establish Rory as a proper and willing companion, to mercifully and timely put an end to the love triangle and move things to post-Rose status so that we can all go on with our lives and Doctor Who can get back to adventuring. But it felt like more than that. In fact, it did a great job of connecting with that novelization feel that Human Nature also nailed. It didn't feel like a TV series, or an action movie, it felt like a story about the characters. A pulpy yellowish book you may have read under a blanket as a kid. Also, old people as alien zombies. That has to count for something.