Whilst I've never really considered it as being top tier television, I have watched the previous two seasons of "Snowpiercer" and never seriously considered giving it up, despite the premise already being stretched pretty thin. That's pretty much the case with this third season too, but I'm glad to hear that the end of the show is in sight now.
With the train split in two, the bulk of the survivor's toil on Wilford's (Sean Bean) Big Alice, struggling to survive the cold conditions and the lack of resources. Andre Layton (Daveed Diggs) and his team on Snowpiercer are following the data Melanie sacrificed herself for but, as yet, aren't finding any signs of recovery. Having found a survivor by pure chance though, and reconnected the trains, Layton uses her and the continued idea of a warmer climate to convince the passengers to follow him.
Having lost one of its stars, with Jennifer Connelly departing the train FOR SCIENCE! At the end of the last season, Snowpiercer provides another season that has its moments, but is largely filler in the continuing saga of Wilfred against Layton. Even with him neutered for some of the season, the story has little else in its arsenal other than his inevitable resurrection. This season sees us also, sadly, lose another of the show's main stars, with Steven Ogg departing midway though (and in a storyline that felt hurried - as if the actor had another commitment to move on to).
Again, to describe the show as a chore is too harsh, it's fine but it's mined its premise for all it's worth and the decision to end the show following the next season is, for me, the right one. That said, the finale does end by offering us at least half of a new idea for that next season.