It basically combines all the best features of music sites I use everyday into one. And there are no ads! There's lots of paid for content when you browse the Discover function, but that is soooo much better than sidebar ads and promoted content in your feed like Facebook and Youtube, or skins and commercial breaks like on Pandora and Grooveshark. I like filling up my queue with full albums and shuffling it up, or browsing mixes. The affinity score is neat. I also like the idea of a social site that is music specific.
The design is slick, but doesn't work super smooth on a trackpad, and I've encountered two glitches so far. But it's a beta . . .
So far, I like it!
Here's a pic of my cover photo: