The media player was the most striking change. It's been totally redone. Everything else appeared to be just a re-skin. US spec car, but only had Spotify in there and no Slacker. I would assume this means we are probably losing slacker, which sucks.
The IC graphics were also overhauled. Better looking, but nothing earth shattering.
Thanks , the move to Spotify has been rumored. Those who have Spotify now complain about the implementation so I hope OS comes with improvement there as well. There are a lot more users of Spotify than slacker so the change makes sense. If we had more choice it would be even better, Pandora, iTunes music, etc