I enjoyed a lot of it and it BLEW ME AWAY that the woman was Tilda Swinton (It looked NOTHING like her!!!!)
And while a lot of it was cool, especially the cars that had the aquarium and nicer areas, the finale and ending were just god-awful. Ruined the rest of the movie for me entirely.
As for the science, it's kinda funny how the perpetually moving train would actually be possible, but yet they missed it entirely on how it would have to be done. They never even explained it explicitly which kinda helps, but it is possible to keep an engine perpetually running (or at least for a very long time) as long as you have an outside energy source to feed the motion i.e. the sun, then you could grow the crops, raise the chickens, and power the engine necessary, as well as melt the snow into usable water.
Of course solar panels efficient enough to do this don't yet exist, this was a movie about the future - so it's not entirely unfeasible. I just think it was comical how cleaning out gunk from a single pipe was an essential piece of equipment to keep the entire train working.