It's what I said about needless arc and hype - if they'd just done the episode and moved on we'd all be thinking "cool, they live out their lives in the past" but by going on about the finality of how they can never see the Doctor again, it just makes us go "but they can if..." Moffat's a great scripter, but their grasp of publicity and guiding the audience is totally borked.
What bothers me is they've been building up three themes with Amy and Rory. One deals with the danger, the Doctor had left them once because he felt he might get them killed and we built up a whole new character in Brian to solemnly ask the Doctor to keep them safe. The second deals with Amy and Rory aging with their travels, lines showing, reading glasses, wanting to settle down. Finally, there's been all the stuff regarding wanting to raise a child and the obstacles there.
So how do we resolve these threads? They get stranded and isolated in old New York. The end.
I just feel it could have been more satisfying dramatically.