In addition to the terrific acting from star Daniel Day Lewis (and to a lesser extent, Paul Dano in a dual role), there were two major plusses about Paul Thomas Anderson's film There Will Be Blood. The first is, I had no idea where the story was going. In an age where it seems that one movie is pretty much like another, this is a welcome surprise.
The second additional plus was the terrific modern-classical score from Radiohead's Jonny Greenwood (including portions of his Popcorn Superhet Receiver). It is the first in recent memory that both calls unnecessary attention to itself (mostly due to its use of dissonance during particularly dramatic scenes) and remains true to the film.
Most of the time, when I notice that I'm hearing a score, it's because it's particularly bad. A good score, most of the time, should be like a good editor: if they're doing their job, you won't notice them. But Greenwood's music outdoes itself on both fronts, making the music from There Will Be Blood also the first score since Danny Elfman's peak in the early 1990s that I am actually considering purchasing on CD.