https://www.apple.com/au/itunes/itunes-radio
Ads are interspliced into the free music stream but you can remove these by paying $34.99 for an annual subscription to Apple's cloud music service iTunes Match.
http://www.smh.com.au/digital-life/digital-life-news/apple-l…
iOS 7 How-To: Use Apple’s new (and free) iTunes Radio streaming music service
Dam…. I didn't think there was going to be ads. So I guess it is just like the free version of spotify