The story opens back in Cardiff, which thanks to the events in "The Unquiet Dead" can now be used as a TARDIS fuel depot. I thought that was a loveley way of thanking the production team's hometown. Mickey comes to visit Rose, who has evidently had quite a few adventures with the Doctor and Jack since the last episode. The crew on board the TARDIS is tight and giddy with shared victories, and Mickey feels very much the outsider.
I enjoyed seeing the Doctor flirting again, this time with Jack. It's a shame our oversexed mainstream culture has forgotten so many of the old rules. Here's one about flirting: flirting can either be a prelude to sex or a replacement for sex. In the latter case it comes from two people realizing that flirting is as close to sex as they care to get, so why not kick back and enjoy it? It's much more bearable than the modern equivalent, the dreaded "can't we just be friends?" line.
The fact that the Doctor flirts with Jabe and Jack says nothing about his level of sexual activity. Some of history's greatest flirts have been celibate, the theory was that it provided them a release valve. I'm greatly releived to see the Doctor flirting for just that reason.
On the other hand it says nothing about his lack of sexual activity, but Rose wouldn't understand and that crew is too tiny to weather that level of emotional tension. Not that this will slow down most of the slash fans.
Margaret the Slitheen is back trying to blow up the world again. The crew catches her, but while they're topping off the fuel tank she takes the opportunity to plead for mercy from the Doctor over dinner. Unfortunately she doesn't understand how to do it. You can feel the Doctor rooting for her, "Come on Margaret! Let's have some genuine remorse, atonement, restitution. Convince me you really will turn your life around if I let you go!" Alas, she fails to offer any real recompense for her deeds, and the Doctor is left to take her back home to her execuation.
BZZZTT! The "overused meme" buzzer goes off again, this time on pregnant brides. So far we've had Jackie and Sara in "Father's Day" and now another one here. Doesn't anybody in Britain marry without getting knocked up first? Throw in the unwed teenage mother from the last story, and you've got way too many out-of-wedlock pregnancies for one season.
Meanwhile, Rose and Mickey are having a date. Mickey is having a hard time dealing with being in effect a sailor's girlfriend. It's a completely different life from anything he's known before, and he doesn't know how to handle it. I once heard a woman whose family has been military since the 14th Century talk about how difficult it is for "outsiders" to adapt to that lifestyle. I can sympathize with Mickey's plight.
Then Margaret's backup plan kicks in, and the TARDIS itself has to save the day. That wouldn't have happened in the original series, but it does follow up on hints that the TARDIS has been growing in sapience over time.
Overall, I really liked the way this episode served as an anchor to keep Dr. Who grounded in reality. Science fiction needs that sort of grounding to keep you caring about what happens next.