IMDb user comments for Purple Rain (1984): "It's no use. Arguments about the potato-chip thin script, the haphazard direction and some of the most laughable non-acting ever photographed for a film, will prove ineffectual. Such conditions have existed in the realm of film vehicles for music stars since the genre began, (with some mind-boggling examples of the worst of the lot offered by every star from Elvis, to Frankie Avalon, to Vanilla Ice.) What you watch these movies for is not the deep plots, solid writing or impeccable direction. It's for those moments of electricity that leap off the screen, strike you right in the butt and have you dancing in your theater seat, as the magic of a performer at his or her peak, in their heyday, turns a few minutes of film into a literal celebration of life."
Yup, that's why I love this movie and bought the soundtrack CD. It really is a great use of celluloid.