I thought this made a satisfying conclusion to Amy & Rory's time as Companions - Amy finally makes once & for all her choice between Rory and the Doctor, and while it was obvious how she was going to choose it still felt like it was a decision with costs that she knowingly accepted. I liked the way they did the fakeouts for what whose fate was going to be - because we knew that Amy & Rory were leaving, we knew from Moffat interviews that "not everyone gets out alive". And so there was tension each time when old Rory died, then Rory & Amy died and then we knew it wasn't over till the headstone with both names on - and they did die, but only after a long life together.
That wasn't the only resonance with their entire story arc that made this such a fitting ending. There was also the "time can be re-written" thing that's run throughout their seasons - not just the first one where that was the actual obvious theme (the one with the crack), but also how Melody their daughter grew up with them. Except that has always come with costs, and this time they reached the point where they couldn't re-write it any more without paying too large a price. Another resonance was old Rory waiting, again, for Amy and not dying till he saw her that one last time. And they also made explicit the Rory dies but comes back trope which has been part of the re-writing time theme.
I liked the way the fixed point stuff was built up. Don't read ahead, because then you can't change it - if you don't know then the future is fluid, it crystallises & solidifies when observed. And it built up in multiple iterations, "why do you have to break mine?" is first only bad because of what Amy could've accidentally read instead, then it's bad because of what it is. And we move from there to the chapter headings, which have their own fakeouts ("Death at Winter Quay" wasn't just old Rory's death, Amelia's last farewell was to River and the Doctor not to Rory) and aren't as spoiler free as the Doctor had hoped for. And finally the headstone which sealed Rory & Amy in the past to live out their lives. Rescuing them now would cause a paradox and that would destroy New York. So the Doctor (and even River, probably) can't go and visit because then he'd probably be far too tempted to take them away for just a quick trip and if they die somewhere that's not Manhattan at the ages of 82 & 87 then *bang*. They're only trapped and lost forever because that's the moral choice, not because they're unrescuable. Which makes it more poignant, I think.
And an interesting counterpoint to Ten & Rose - Ten burned up the energy of a star to talk to Rose one last time in the other universe. But Eleven and Amy & Rory aren't going to risk blowing up New York for the sake of another few years. Lower price, higher reward, but still not considered.
Very thematically appropriate for it to be the Weeping Angels. They weren't there just because they're the monsters that send people back in time. They were there because as long as you're looking they can't move. Solidified. I think this was a better successor to Blink than the other Angels one, because it went back to them sending people back in time, and because they went back to creepy.
One thing I'd seen mentioned elsewhere on the web between last week & this week was that perhaps the Doctor was visiting Amy & Rory out of order - there was some mention of his age in one episode, and some adventure mentioned earlier than we see Amy & Rory doing it (to do with Henry VIII). That wasn't really touched on this week (if it even exists). It does make me wonder if the Doctor that stays with Amy & Rory in the last episode (The Power of Three) is in fact not long after he loses them in his timeline - he does make a point of saying he missed them. And then his reaction to her asking why it's so long between visits in Dinosaurs on a Spaceship one isn't because he is or isn't weaning them off him but because now she's said that he can't go back to fill in the gaps. Spoilers solidifying time.
Or perhaps that's all a load of rubbish & it either isn't even happening, or will be touched on in the next half of the season ;)
Another thing that may or may not mean anything - Amy suggests in the afterword that the Doctor won't be "coming back here soon" ... does that mean the next Companion won't be from 20th or 21st Century Earth? That'd be a nice change.