I think the fact that a vast majority of its fans thought the ending was awesome easily trumps a few dissenting celebrity voices making glorified forum comments in front of a megaphone.
I would also say one of the signs of a truly good show is when the last season had significantly higher ratings than the first season. Breaking Bad's fourth season ended with 1.9 million viewers, which was considered a big success. The last run was consistently over five million and the finale broke ten million. That kind of late series boost is unheard of in television and only happens when a show has insanely good word of mouth.