After 5 enjoyable (if sometimes flawed and rushed) episodes the series ends with a stand-out classic. Steven Moffat has written another episode that ranks right up there with his best (not as high as Blink though, but then I doubt he'll ever top that).
BBC America (a separate company from our BBC across the pond) providing funding so they could really shoot in Manhattan was a plus. Actually showing the city was one of the myriad reasons why this was so much better than the last episode set in Manhattan – the execrable Daleks of Manhattan (personally I'm hoping that the paradox-forming actions of the Ponds has also erased that episode from history).