I got to play around with it on a Galaxy SIII at work, the UI seemed laggy, but it was okay. The genre dial is cool, but not necessarily the best UX. However, it does resume from the exact place of a song you were on if you accidentally change genres.
It's powered by Slacker Radio, (which I already enjoy on Android) so any non-Samsung owners can still have a similar music streaming experience through the Slacker app.
We thought the dial Samsung did in the UI was a rather fresh approach to solving how quick a user gets an overview of genres, and preview stations without having to 'commit' to them.
I'm excited to see Samsung push this along.
Typical tasteless Samsung design on this page. So ugly
Did they know there is a band by the same name (http://www.milkmusic.us/)? They've been around for 4 years!
Doubt the band trademarked the name.