These guys like playing guitar with a bow. A lot. The music is actually very sophisticated and atmospheric. A lot of people call them "ambient pop" but that's a misnomer. "Ambient" implies a lack of movement; in fact, Sigur Ros' music grows and moves more in the course of one track than most contemporary music does over the course of an entire album. Definitely worth a listen. Pick up Agaetis Byrjun first.
"Hey, you know, these songs all had titles when they toured this material for a year and a half before recording it. Like this first song was called 'Vaka'."