Today it looks classic, in much the same way that such masterpieces of midcentury modernism as, say, Mies van der Rohe's Seagram Building or Frank Lloyd Wright's Guggenheim long ago ceased to look "modern, " at least in the informal sense that most people have in mind when they use the word.
WSJ: Long After the Initial Shock, Modernism Still Delivers | Sightings by Terry Teachout