Seems like a lot of movies listed here are panned by critics and fans alike, so saying they are underappreciated is really just a person saying that critics and fans are wrong, right? Instead, I would list movies that are are either misunderstood (like, say, Holy Mountain), or are generally considered good, but are not appropriately appreciated would be better understood as "underappreciated." Taking that tack, I would list Miller's Crossing as an underappreciated movie. Highly critically acclaimed. Made by the Coen Brothers, brilliantly written, acted, and executed. But you rarely hear it listed among the best of their movies, or as one of the best movies of the 1990s. Even Barton Fink gets more acclaim, possibly because it is more of an art film. So, I say that one is underappreciated.