As it turns out, not everyone was wowed by this musical evolution. No less a light than the legendary composer Bernard Herrmann (Citizen Kane, Taxi Driver) declared: “It shows vulgarity, when a director uses music previously composed! I think that 2001: A Space Odyssey is the height of vulgarity in our time. To have outer space accompanied by The Blue Danube, and the piece not even recorded anew!”
Then again, maybe Herrmann was just showing solidarity with his fellow film composer Alex North, who only found out that Kubrick had abandoned his full, lush orchestral score for 2001 when he attended the film's premiere screening. Not cool, Stanley... not cool.
The Open Culture article ends thusly:
Thanks to Spotify, you can listen to over four hours of classical music that Kubrick used in his movies. Find the playlist below, and a list of the classical music in Kubrick films here. The playlist features everything from Beethoven (A Clockwork Orange) to Schubert (Barry Lyndon) to Bartók (The Shining). If you need to download Spotify, grab the software on this site.