It also depends on where you are in the world. For instance I can legally use filesharing all I like because I live in Canada and sharing is not illegal.
Personally I use a mix of itunes and filesharing. If there's a bunch of music I like listening to but is just okay, torrent. If it's only one song off an album or something, then I buy it off itunes. But I generally do not like all of the songs on a CD, and more often than not, I only like one or two, so buying the CD is like paying $25 for two songs. No thanks.
I also find it ridiculous that there's only a big uproar about people sharing music and such since it became so easy to do with the internet and media files. Back when it was just copying a cassette they didn't like it, but sort of turned a blind eye because it didn't bite into their huge profits. (The record labels, I mean)