I like it, the slickest interface of the iPhone players available so far. And to be able to listen to legendary stations in other parts of the country is great.
Another good thing is it will adjust the stream rate to the available datarate, on Edge you get a lower quality stream, on WiFi & 3G you get a high-quality stereo stream with audio better than satellite radio.
But as I mentioned in another thread "Tuner" ($5.99) gets my vote for favorite because of the sheer variety of streams available, plus being able to enter more streams if you have the address.