This movie has some good music and dancing, in a sappy plot. But the music and dancing are not integral to the plot development; they do not carry the film in the way dancing carries "Dirty Dancing" or "The Turning Point" (both of which have better dancing, by the way.)
But it's one of my favorite movies. Why? The director, Adrian Lyne, got his experience directing TV commercials, where the entire message has to be conveyed in 60 seconds, and in Flashdance every moment is contributing something. The key is the cinematography. Leonard Maltin calls Lyne a "visual stylist", and he is, but he's more. He takes Roman Polanski's cinematographic innovations and pushes them to new limits; the camera tells the story.
When you watch "Flashdance", watch how light and camera angle are used. Light: Pittsburgh light, hazy, smoky, dull, reflecting off puddles, blazing from lamps, dim, bright, strobe, whatever; lighting carries the mood of each scene. As for camera angle, in most movies we are observers, outside the movie, watching the actors. In some of "Flashdance" that is also true, but then in many places the camera angle shifts so we are inside the movie, seeing what one of the actors, or several of the actors, see at that moment. It just pulls you in. If you're not familiar with the film, the first time you watch it wait for the final "audition" scene, and watch how the camera is first an observer, before the dancer enters the audition room, then sees from the dancer's view as the audition begins, and then shifts to show us what the judges see, as the dancing becomes compelling. I don't know about you, but this grabs me and pulls me in; I could watch that scene five times running. And there are many other scenes in which camera angle is used similarly but not quite as obviously. I give this movie four stars; I would give it five if the music and dancing were as well integrated with the plot as in some other movies.