Doctor Who: "Partners In Crime"

And we're off. Season four of the new-look Doctor Who begins in high style with an episode that gives The Doctor a new(ish) partner, dangles some clues about the season to come, and contains a whopper of a surprise near the end, at least for those who have safely avoided spoilers about this season. I'm just going to assume that everyone reading this entry has seen at least this episode so that particular spoiler will be in this post. Fair warning.
Russell T. Davies pens this week's episode. I was surprised by the Davies antipathy in the comments last week given that a) I've generally liked the episodes he's written b) Davies' seems responsible for the overall structure of the show and the tightness of each season and the ease with which one season led into the next has always impressed me and c) he is the guy responsible for reviving the show after all. Is this an old-fan versus new-fan divide? As someone who came to this show only in the Davies era I don't necessarily have the best perspective on this.
Anyway, back to this week's episode. It opens with a shot of Catherine Tate's Donna, last seen rejecting The Doctor's offer to travel the universe in the TARDIS two Christmas specials ago. We're soon to find out how much she's regretted this decision, but only after The Doctor and Donna spend the first half of the episode almost-but-not-quite crossing paths as they investigate a sounds-too-good-to-be-true weight loss scheme called Adipose.
Okay, scratch that. Adipose is too good to be true. Working separately, both The Doctor and Donna discover that it's "The Fat Just Walks Away" slogan can safely be interpreted literally. Turns out that it's a front in which an alien race uses overweight customers as unwitting sources for tiny babies made out of fat. (There's a joke in the episode about the aliens choosing the U.K. as a particularly fine source of fatties. It offended my American pride.)