Citizen Kane is a phenomenal film, and it's still great despite its age. Everything about this film is perfect: the acting, plot, characters, and especially the haunting and powerful ending. It's not a very happy film, but it's fascinating and definitely a must-see.
As far as content goes, this film is refreshingly free of language and drugs. There are references to an affair, and one character becomes angry and begins to trash furniture and objects in his room. This film might be a bit confusing for young kids to follow, because of the unusual way it is presented.