This is one of the great American movies. The reasons for its obscurity have everything to do with mass consumerism in the late 20th century and nothing to do with its quality. In my opinion this film captures the essence of the late 1960s better than Easy Rider, The Graduate, or any of the other popular films that have come to be associated with that era.
Wexler combines a very European (Italian Neorealist/French New Wave) style with a very American subject matter in a way that comes across as completely natural. It is an art film that plays like watching the evening news.
It is exciting both formally, and culturally: not only does it provide a lasting document of the late 1960s counter-culture in conflict with the aging, square America of the Eisenhower era, it more specifically does a fine job of representing the more general cultural conflict of rural people (here white Appalachians) thrust into the Yankee city environment.
All this, and the movie is fun to watch, not some intellectualized snorefest. It a great movie.