The sign of a classic movie is how well it ages and "Close Encounters ..." seems to get better over the years and the more times you watch it.  This film has many signs to show that it was influenced by Stanley Kubrick's masterpiece "2001: A Space Odyssey" from the opening sequence to the massive role of music to the whole feel of the movie and yet Spielberg did not simply copy Kubrick's formula but instead took the genre on to another level putting his own stamp on it.  Franchises like The "X-Files" and many others have at least been influenced themselves by this film and the special effects are spectacular for the time given there was little if any CGI to the scale of today and yet the visual effects hold up very well even by today's standards.