No, the correct answer to the question of what was the WORST finale EVER is clearly "The X-Files." It was not only bad, not merely disappointing, but downright insulting. After loyal viewers had tolerated Chris Carter's ever-more obvious lack of a clue as to where the whole thing was going, they were treated to a finale that was largely a CLIP SHOW, draped loosely on the premise of some kind of trial of Mulder! Who did they think was watching the finale? First-time viewers who needed a refresher on "the story so far"? No, this was bad on all levels.
But it may not end up as the last word on bad finales. The Wife of Solipsist (WOS) voted for "Lost" pre-emptively. We'll have to wait another season-plus for the verification, but the fear here is that the writers and producers never really expected the show to be as successful as it's been, and so they've, you should excuse the expression, lost themselves in a branching labyrinth of multiplying storylines that not even Theseus with all the string in the world could find his way out of. Remember folks, you read it here first.