Check out this review: http://reviews.cnet.com/mp3-players/oakley-split-thump-2gb/4505-6490_7-32740046.html
The audio quality isn't going to be AWESOME...but you probably won't notice unless you're an audiophile.
As just an MP3 player, they aren't worth it, but as a combo of MP3 player and sunglasses, they seem to be quite good. Assuming the cost isn't an issue.
