Snowpiercer was a brilliant movie. Not the plot, that didn't really matter. And of course there's a lot of rather implausible things going on. But the cinematography, the choreography, the directing, were all fantastic. The axe battle scene in specific was a great homage to Korean films (there's some film in specific it draws from, but I'm forgetting on the name), which makes sense as the directory, Joon-ho Bong, is Korean. The acting was pretty good too, I especially loved Tilda Swinton.

There's also arguments to be made about the philosophical message of Snowpiercer, but I don't think that's particularly relevant to why the movie is great (though obviously others disagree).