On 4G (I have an unlimited data account) every time I try to open Spotify it can take upto 5 min to load. This is followed by a further 5 minutes loading any particular song. I also get a error message saying poor data connection or no data connection. However looking at the top left of my display it is showing 5 bars with the 4G icon showing.
If I was to switch to my home network the time taken to load and play is dramatically decreased.