I was originally a subscriber to Google Music but the iOS app (I last tried it about 4 months ago) is absolutely terrible. Streaming didn't always work well and when trying to cache things it would constantly cache broken songs with many issues with them. It was impossible to use every day. I had hoped to stay with it especially since I got in on the $7.99 deal but I need the music to actually work across all of my devices.
I use Google Music only for the library it offers of my own uploads. The iOS app works pretty well now, a new one was just released that didn't spoil the fun. I don't use any of the paid service.
