Snowpiercer movie review

I didn't hear about this movie until it was mentioned in a list of movies never released in the theatres in Hungary that were good. That's where I live, BTW. The concept sounded interesting and unique, so I decided to check it out. I also do have a thing for dystopias.
The movie is about a train that goes around the world, carrying the last members of humanity. In an experiment that we managed to mess up, we managed to freeze the whole world. The train was built to be a self-sustaining economy. I did wonder how that would work.