I'm a Premium account user and use both the mobile and desktop versions, mostly mobile on my iPhone 4. After a recent 'update' to my Spotify app, I can now no longer rearrange playlists on my phone. This is a terrible downgrade, as on-the-fly rearranging was one of the main reasons I loved the app and justified paying for it monthly.
The only solution I've been able to come up with is to install the old iOS4 Spotify app, arrange my playlists on there, and listen using it or the new version of the app. This is so inconvenient though. I saw somewhere that a Spotify developer said this function was taken away in order to expedite the release of the new Spotify app, and that the function would return once they had figured out how to make it operate properly without crashing. WHY? I would have rather kept my old Spotify app (not the iOS4 one) if I had been told I can't rearrange playlists if I update.
If the function doesn't return I would honestly consider cancelling my Premium subscription, and I know the other members of my band would as well. I just want the functionality the app once had. 😛