I saw Phantom of the Paradise pretty much when it came out in 1974. I've got to tell you, it looked goofy and dated then, too. Trying to sell Paul Williams - who wrote "We've Only Just Begun" and "Just an Old-Fashioned Love Song" - as a glamorous Satanic demon? He's about as evil as Barry Manilow. OK, maybe I see their point.
Anyway, Paul Williams is Swann, a rock producer/impresario whose big stars are like an evil version of Sha Na Na (that is, like Sha Na Na). He hears geeky singer-songwriter William Finley singing part of his rock cantata "Faust", promises him fame and fortune, steals the music and dumps him. This causes Finley to seek out revenge, become hideously scarred, get a cool costume, haunt Williams' rock palace the Paradise, etc.
Meanwhile, both have fallen in love with aspiring singer Jessica Harper. Actually, it was the Movie Morlocks article on Harper that pushed me over the edge to watch this again. She does have a nice voice, although it doesn't get much of a workout here. Reminded me a little of Sandy Farina, from Sgt. Pepper. But I don't know if she really sold the rock diva thing - or even the rock innocent.
That's pretty much the whole problem with this movie: Williams' score isn't very exciting. Harper wasn't exactly electric. The big sub-Rocky Horror glamrock stage show finale just looked silly. It was all too goofy to be evil, and too earnest to be goofy.
And Paul Williams!?!? I'm not saying they should have gotten Bowie or Iggy Pop, but James Taylor would have been more threatening.