I've watched Avatar, I don't think I've watched the entirety of the series but I've watched the majority of it including most of book 3 and the aforementioned ending. To be totally honest the series isn't half bad, the biggest issue I have with it is no fault of it own, which is it is often mistaken for an anime. . .
I'm not sure when the sequel will be aired down here nor do I think i'll personally be watching when it does, but i'll eventually end up watching some/most of it when Nickelodeon runs the damn series into the ground with never ending marathons of it that i'll eventually be bored enough to watch. . .
whats the bet when the show is about to debut, Nickelodeon down here will decide to marathon the entire original series yet again so people can get up to speed.