Nods to the past and the foreshadowing of things to come. For those of us who have seen Pond Life, we have already glimpsed the relative chaos that having the Doctor in your life can bring.
This story was about the two lives which Amy and Rory lead, set against the backdrop of the latest alien attack on Earth.
We learned as much about the way the Doctor thinks and feels as we did about the Ponds. He wants to spend as much time as he can with them before they inevitably fade from his life, and because he misses them. Amelia Pond was the first face he saw with his new face - and she has imprinted herself on him.
There have been almost constant criticisms from old school fans that "Nu-Who" never stops for breath, that there isn't the time and space for character development in the way you could with an old 4 or 6 parter.
It's a view I've never subscribed to. I have become emotionally connected with characters throughout the last 6 and a bit series - and not just the companions. I've shed a tear at deaths and departures (lord knows what state I'm going to be in this time next week).
This entire episode was a chance to pause and examine this particular Doctor / Companion relationship, and within it there were little pauses as the main plot motored along.
I'll get that main plot out of the way now, as in may ways it was simply a Hitchcockian "mcguffin" to hang the real story on. An ancient alien race, the Shakri, want to prevent Mankind's eventual spread throughout the universe. The Time Lords thought them a myth. They're described as a form of intergalactic pest control. The cubes have been sent to study human beings, then use the knowledge gained to destroy them. The slow timescale of the Shakri plan is to enable people to get used to the cubes - to take them into their homes and workplaces. When the attack comes, it's in the form of induced coronaries. The quick fix is to reverse what they do - to restart stopped hearts - and there is a convenient power overload to destroy the alien ship.
As alien plans go, it was either a bit thick or just badly timed - attacking when the Doctor is in residence.
Shakri, played by Steven Berkoff, was an interesting character who I'd like to have seen more of. He doesn't appear until the final 15 minutes or so. Costume and make-up were suitably sinister. References to the "Tally" and wider universal issues might allow for a future story arc.
Back at the real story, we learn that it has been 10 years since the Doctor came back into the adult Amy's life. The Ponds are struggling to hold down jobs and a home-life whilst being at the Doctor's beck and call. They don't have to go with him - they just want to. Rory's a part-time or agency nurse, and Amy's now taken up journalism. Their lifestyle means there are domestic dramas to contend with - from failing to keep important appointments with friends, to finding the milk has evolved into a new life-form while they've been away. During this episode, we see them disappear from their own anniversary party for 7 weeks - encountering Zygon duplicates at the Savoy Hotel, and King Henry VIII.
Only Brian Williams notices they've been gone (a welcome return for Mark Williams who is superb throughout. Shame he has been introduced so late in the day). There is a lovely scene between Brian and the Doctor where the former asks about the others who have travelled in the TARDIS - forcing the Doctor to admit that, just occasionally, they die.
The other stand-out scene is the one between the Doctor and Amy on the Thames riverside where he defines what their relationship means to him.
A special mention for Jemma Redgrave, who gives a wonderfully understated performance as Kate Stewart, special scientific adviser to UNIT. A Stewart in UNIT? She couldn't have been anyone else, could she? The Brigadier's daughter, changing the organisation from the inside to be more science-orientated than militaristic - stuff her old man had learned from his old friend. I sincerely hope we will see her again.
A lot of previews mentioned a return for some RTD era staples - the news reports (with real BBC reporters - but no Trinity Wells, shame) and the celebrity cameo. We got Sir Alan Sugar trying to get his apprentices to market the cubes, plus the man who makes particle physics sexy, Prof. Brian Cox.
I must admit that this is the story of series 7 I had been most looking forward to. Yes, there were Daleks, Dinosaurs and Cowboys coming up, but I knew this one was going to be different. So long as you don't get too hung up on the cube / Shakri plot, this is an absolute joy of an episode. A lot of humour and quiet, human moments. I wasn't disappointed.