I knew the music to this film for many years before I finally saw the film itself. I had discovered the hypnotic soundtrack by Rheingold on a second-hand LP and have had it on heavy rotation for many years. It's one of the best albums I know.
The music is certainly one of boons which helped to put this movie into another class and make it a classic. Hypnotically slowly, it follows the development of a teenybopping waif's obsession with a pop star spiraling out of control. It's one of those movies which you kind of have to see in a cinema because on TV you'd zap away after 10 minutes. But it richly rewards your for its slower moments.
Apparently there was a lot of controversy around lead actress Désirée Nosbusch's nudity scenes, which are admittedly surprisingly crass. But they are not exploitative and absolutely gel in with the movie. Kind of ironic that immediately after this scene there is one of extreme violence which went practically unnoticed by the public. A nice society we're living in.
It's very respectable that the director fought to keep these scenes in, as they are essential to the escalation of the story. They are actually a good example of how those scenes should be done realistically but without becoming pornographic or voyeuristic. It's a big fat shame that this controversy tainted the reception and popularity of this great movie.
And by the way, other than is often stated, the affair between star and fan doesn't end with the star "dropping" her after a night of carnality. It's not a case of "find'um, furp'um and flee". R. merely returns to his reality whereas Simone stays locked in her fantasy world.
Some tidbits about this movie: R. is actually played by the singer of the band Rheingold, Bodo Staiger, which furnished the soundtrack. The actress playing the fan, Désirée Nosbusch, was at the time already a popular "VJane" (i. e. hostess of a music show like the one that is shown in the movie). And the host of the TV show which Simone watches with her parents at the beginning of the movie is played by Joachim "Blacky" Fuchsberger, who in real life was the most popular TV host in Germany at the time.