I thought the way it started as a flashback type thing with Amy's voiceover was going to turn out to be interesting. Bit of a shame it seemed to be mostly to let them make the lame pun of a title explicit.
This felt like quite an old school Who episode, what with UNIT and callbacks to the time the Doctor spent on Earth in his 3rd & 4th regenerations. K9 was mentioned, the Brigadier too. And still a more personal level of story, even if it was an invasion of the whole Earth - we're still a step back from the universe destroying stories of recent seasons.
I liked part of the way the Shakri designed their pest extermination tools, it really is the way that would work - the initial worry & panic about the cubes followed by them just becoming part of the way things are. And then they switch on & do their stuff once we've relaxed. Perfectly designed. But other than that - why did they do a count down in arabic numerals, but not an Earth time unit? I mean either it was designed to tell us or it wasn't.
I was also a little unclear why they were stealing people as well as doing their thing with the cubes analysing us. I mean, either the cubes did the scan/response tests/whatnot or they looked at the people they stole. Felt a bit like they stole people so that there was a way for the Doctor to go & stop them. Which felt resolved a bit too quickly to be honest, right up until the end I thought it was going to be a two-parter but then Doctor just waves his screwdriver & everything is sorted out. But there's still a ship, and the Shakri presumably aren't going to give up just like that. Maybe it's going to come back in the second half of the season? Maybe they're just going to become vaguely recurring enemies in future.
No fakeouts with "the Doctor" not being him this week - but then he spent years working for UNIT so of course they meant him. Nice touch having Kate Stewart do the scan, show us two hearts to remind us why the heart stopping device wouldn't work on the Doctor for people who don't just automatically know he's got two.
The fakeout that did happen was when it looked like Rory & Amy were choosing to settle down. That was also one thing the voiceover thing did well, telling us how they were choosing between the two lives and showing what the choice was. They might even have done that too well, because the reversal at the end where Rory's Dad persuades them to go off and adventure again seemed to come a bit quickly.
More anvilicious hammering home of the "sometimes companions die" thought. Which I suspect means it won't quite work out like that, but it's going to look like it's going to. Or maybe I'm wrong, and one or both of Amy & Rory will die.
Interesting the "imprinting" of the Eleventh Doctor on Amy, I did wonder why these people were supposed to be different to any of his previous companions although that explanation does leave one wondering why it didn't seem to work that way before. But I think that's something we're just supposed to handwave past ;) (And it does work for Ten I suppose, as the Rose/Ten dynamic was also clingy).
Hmm, seems like I did have stuff to say :) Overall I did enjoy the episode, but it feels like the weakest of the 4 we've had so far this season.