This entry seems a bit premature since we're in the middle of the story and it's a true two-parter filled with all sorts of questions we're not going to get answered until the next time around. More to the point, it feels a bit like wheel-spinning before the real action begins. Did we need such a slow build-up? Did we need that 20-minute (or so it felt) bit with the two slow-witted UNIT soldiers deciding whether or not to open an obviously dangerous casket of goo? How about Donna flashing back to all her most treasured moments from her past adventures with The Doctor, all five of them? (At least this was in the BBC cut. I can only assume that Sci-Fi cut it from American airing and, for once, I understand.)
Not that it was a bad episode, mind you. And it was certainly better than writer Helen Raynor's last Who script, the dreadful "Daleks In Manhattan"/"Evolution Of The Daleks" two-parter. That one had a great premise (Daleks in 1930s New York) but dreadful execution. This one has a fairly familiar premise, echoing back to season-opening "Partners In Crime." But I'm intrigued with where it's going, even if it feels like we've been here before.
Looks like this series has a bone to pick with corporate culture this year. First we got the stealth fat babies of Adipose. Now we get the alien GPS system Atmos, a great source of directions so long as you don't mind getting killed every so often. (Has anyone really taken a good, long look at Garmin?) It's a classic bit of technophobia–I can imagine a '90s Who series doing something similar with cell phones, if one had been around–but the real target here isn't the gadget but the gadget-makers.
There's quite a bit of old Who business in this episode. Both UNIT and the diminutive, militaristic villains the Sontaran come from the old series. I don't know if they've ever been in episodes together before (readers?) but the pairing gives the Doctor a chance to take some not-so-subtle jabs at military culture in the modern age. Tennant's reading of, "Oh, don't salute," is pretty priceless, as is the phrase "Homeworld Secuity."