After messing with this for a day, I am a little underwhelmed. It's cool that there's one radio station that the whole world is listening to at once. But I keep hearing the same songs, and without that much time having passed.
I also don't like how it integrates songs you don't own with songs you do, all in your library. I am not opposed to buying music and I do it fairly often. I use Spotify to listen to music I wouldn't pay for. I liked how they were separate. Spotify is music I don't own, iTunes is music I do. Now it's all just crammed together in one place and I feel like it really trivializes music I own by mixing it with all this crap I'd never spend money on.