I have an Iphone 4 with IOS 7 and the latest version of the Spotify app.

1) This has happened several times. I click shuffle play on one of my playlists and I get a message that says unable to play track. Mind you I am using different playlists with well over 100 songs from Spotify's library. 

2) Other times I have noticed when i am switching between playlists using shuffle play a song that is not associated with a certain playlist will play on the wrong playlist.

3) When I play local files, the artwork doesnt come up and the song does not show in the lock screen. It will instead show the previous song I have just played in the lock screen while my local file is actually playing.

4) The app is slow and unresponsive at times.