While theres truth to your assessment, Bullwinkle, I had a much more positive feel towards the finale. When they announced last year that it would be the end of the series, I think it forced the writers to cut stuff they had planned in order get to the ending a bit more efficiently. I had read somewhere a few months ago that they had hoped to have 2 more full seasons to bring the series to a close and that they had to reduce 44 episodes down to 13 to finish the series. You could see the effects of that in that at times this season seemed a bit forced. Still, as a whole I thought they did admirably, under the circumstances. As far as the finale, I thought they did a good job of referencing a lot of the earlier episode stuff and especially enjoyed their assault on the Observer HQ. It was definitely peppered with shout outs to the series as a whole and a nice send off for the loyal fans.
I caught a few of the references in the assault (I have a friend who played the guy that first got the slicing butterfly attack way back when), but not all, I'm sure. Not all of those needed a handholding explanation before hand (the assault certainly worked without it), but certainly the end moment did. While I vaguely remembered the referenced episode when I looked it up, that was three years ago! A lot has happened in between, and, as far as I know, it hasn't been referenced since.