I use Pandora A LOT on my iPhone 4s (also on my previous 3GS). Never had a problem at all. Just tap the Pandora icon, and I'm listening to "my" stations. Once logged in, always "on". Also, I never "sign out" of my Pandora account on my iPhone... sometimes, I'll "end" Pandora on the multi-tasking bar (double-press the home button). But even after that, just tapping on the Pandora icon, and I'm listening again... no fuss, no mess. Note that I set up my Pandora account on my PC, and log in on my iPhone using that account. Also, I set my playlists on my PC... but I think I also may have changed my playlist on my iPhone too.