Well, i watched the tv series. It is indeed good imho. Why do you ask?
Well, while the class warfare metaphor is there, one can ignore it for the issue that these people were never supposed to be in this situation to begin with. As i understand it, the lowest class are people who just forcefully boarded the train when it was first departing on its endless trek. The global warming was reaching horrible levels so the scientists decided to pull a hail mary, introducing a chemical process that basicly resulted in a nuclear winter analogue.
The Snowpiercer was not concieved as some cold fusion perpetuum mobile engine, it was one very rich mans personal project. The fact that the visionary had to be replaced almost instantly because he was a megalomaniac control freak is also another matter. The crux of the situation is, metaphor or no metaphor, the train is not some marvel, its a powder keg thats degrading while the people inside are all dealing with intense pressures. Its gonna stop eventually, either by exhausting the resources, parts or by that pesky human element. And it makes for some neat entertainment.