Ooh, I liked that. It was pretty much what I was expecting, in terms of it being a bit of an action/thriller type of episode; UNIT were way bigger than they ever were in the classic series (which is probably a good thing) but the new commander (Mace, was it?) was nowhere near as good as His Brigness (but then who would be). I have vague hopes for a surprise cameo by Nicholas Courtney in the next episode, but I'm probably not being very realistic there.
And yay for the "I worked for [UNIT] in the seventies" comment! Yay, UNIT dating resolved once and for all!!! (As if...)
Martha's return was well-handled, on the whole, up until the moment when she was gullible enough to follow the possessed UNIT soldiers into that room.
And I could have done without her screaming.
And frankly, I wanted to see Martha, not Martha's evil
Hopefully Martha (and/or Freema) will get a bit more of substance to do next episode.
Nice stuff with Donna's family too - her mother grates a bit, but that's just because the character is written and played deliberately to have that effect (I hope), but aw, Wilf! Bless!
Also aw to the flashbacks, 'cos it was nice to see flying waving Adipose again. *g*
And the Sontarans were incredibly effective. Probably the best they've been (although I've not watched Invasion of Time properly since it was first shown...roll on the forthcoming DVD). Very impressive, although I could have done with them having fairly similar voices to each other - Staal and Skorr were too different considering they're meant to be a clone race. At least The Two Doctors got that right!
So yeah - generally good, and hopefully the bits I wasn't happy with (i.e. messing up Martha's return a bit) will be corrected next ep.
Oh, and what the hell accent did that Luke Rattigan have?