I know that Robert Baird did not like it so much (http://blog.stereophile.com/musicroom/robertbaird/022508loud/) but I thought Jonny Greenwood's score for There Will Be Blood was impressively well done. Sure you can say that he's a Radiohead guitarist ripping off classical composers, but I thought it was all very smartly done & greatly added to the movie. (The film, as good as it was, is not even close to The Citizen Kane, however.) I thought of Penderecki and Toru Takemitsu, and the more lyrical passages sounded like Messiaen (a composer that Greenwood's very fond of.) The suspenseful sections - the plucked ostinatos & percussion - reminded me of Bernard Herrmann's work for Hitchcock, albeit in a very different way... but had a similar impact on me. I cannot imagine There Will Be Blood w/o this soundtrack.
I liked the soundtrack more than the movie. But I thought the use of Brahms violin concerto was extremely distracting (once during the movie and again over the end titles) and unrelated to the events onscreen. I wonder if Greenwood wrote something for those spots that the director didn't like and replaced with Brahms...?
Yeah, I thought the use of the Brahms violin concerto at the end was too cute. A lot of film critics liked it, but I thought it was ham-fisted. Sort of a tongue-in-cheek throw-in to say, look, we've subverted a genre. A cheap ending.