I have one of the Zen Vision M's the 30 gb - sound quality is excellent through my Sure E2's. I imagine the original buds are terrible, but then all the ones they give away are including the Ipods famous buds of mediocrity.
As a player I really like it, I didn't go for the Ipod as I can't stand being forced to use Itunes - with the Zen you can use the creative software which isn't very good or Windows media player which is my prefered option or you can just drag and drop onto the hard drive.
Excellent player, easy to use, good battery life, great screen and good sound quality as long as you get a decent set of earphones for it.