I'm not an audiophile, but to me they sound ok.
Comparing them to my ksc75s, I'd generally pick the koss, but it isn't a drag to use the vmoda earbuds, especially if I'm not listening to something where the bass-heavy kosses aren't as appropriate. In really "full" sounding music like alternative or metal where there's lots of electric guitars and things going on, they can sound a bit ... shiny? Brassy? Like it's all smooshed together into "noise." But for pop or electronic or classical they're pretty, and there seems to be a reasonable amount of bass for earbuds. This is all just me sitting here trying to listen for defects. They're perfectly fine to walk around with, no matter what you're listening to.
I was going to try to compare these to the only other earbuds I have -- my ibuds -- but those have stopped working, it seems. I'd imagine they're better, because my kosses and shures made me toss the ibuds into the drawer and leave them there, whereas these v-moda things I actually use.
That said, I got these for free and I might not buy them again if they break. Unless you have a specific reason you want earbuds rather than clipons, the kosses are the better deal. (Much cheaper, and maybe about as good or better, depending on your music.)
That said, they're really shiny and the cord is awfully cool looking -- braided wire of the same color of the phones covered in clear plastic -- and they do sound nice. They'd be a good suggestion for the "what headphones should I get my girlfriend, they have to be pink?" posts that occasionally show up here.