I took a Music in Film course last semester, and it really helped me realize the importance of music (or lack thereof) in a scene.  It really adds a psychological subtext to a film that could be otherwise impossible. 

For instance, before film scores were widespread, the film "The Lost Weekend" was screened with no intentions of adding music.  It was supposed to be a serious film about the effects of alcoholism, but the audience laughed throughout most of the drunken antics.  A dramatic score was added to the final cut, and the mood was completely flipped, making it one of the best dramatic movies of its time.

On the other hand, I thought the lack of music in No Country gave it a really weird vibe.  The gratuitous violence with no music (and none of that dramatic bullet-time slow-mo crap) gave it a very shocking, realistic, and at times even depressing effect.  I don't see what the big deal was about this one.  Critics and some people I know have been raving about it, but I didn't see anything too spectacular.  It's supposed to be based off a book, so maybe I'm just missing some underlying themes (only watched it once).  Hard to get into a character's head when there's little dialog and no music to set any mood.  Actually, I don't even see how the title pertains to the film. 


edit:  also, didn't Falling Down lack a film score?

The China Syndrome