The score by Miles Davis is often called "groundbreaking".
I watched it at Hulu, free with commercials, but they've put it back behind the paywall now.
Slant Magazine praises the score. HorrorNews.net closes by saying, "much of the film is groundbreaking, not only in its juxtaposition of sight and sound but, in the angular editing style, serrated narrative, and of course the film’s influence on the noir genre." Bright Lights Film calls it "a fantastic period piece".
Roger Ebert gives it 3.5 out of 4 stars. Rotten Tomatoes has a critics score of 92%.