My wife and I just finished the finale tonight, and it was a great ending. Very little ambiguity, real closure, and an emotionally appropriate song.
But, I think it is far from "the best TV show". It may have been "the best" for a TV drama when it came out because it was groundbreaking, but the acting and writing at times could be pretty bad (so many dropped plots with no follow-up or consequences). It also went on for far too long, which was a consequence of having to create 12 episodes per season, each the same length.
It's worth watching, but I'd give it a 7.8/10.