Holy smokes, this show is great. IMO it is MUCH better than the movie. This despite the fact that I always thought the central premise is a bit....odd, albeit very interesting, I have been getting really into this, and I can be pretty hard to please.
For those who don't know the premise: the world has gone into a deep freeze, and humanity's survivors are all stuck on a train in perpetual movement, driven by some sort of eternal engine that also keeps them warm. Passengers are strictly divided into 1st-2nd-3rd class, and then you have the "tail" people who actually strong-armed their way on board and have been treated like garbage ever since.
The TV show feels much deeper and more complex than the film (again IMO)