I never even knew Google music was a thing until now.
I prefer it to any other streaming service.
If you don't buy the subscription it lets you upload 20k songs to their servers for you to play back on any device you're signed in to.
If you pay for the streaming service [$9.99/mo] it also lets you stream any other music similar to Spotify and such. Google also recently bought the service Songza which they implemented into their Google Play Music platform to better generate playlists like the ones pictured above.
Google also introduced Music Key for YouTube recently, where if your Google account has a Music subscription, you can watch music videos on YouTube ad-free.