Google Music used to allow you to rate your songs from one to five stars. Though it was a feature that you had to add on, for those of us who did add it, we used it all the time to help sort and organize our music. Today - May 14, 2015 - Google removed this option. This is their response:
"We've decided to remove the 5-star Rating lab. This decision wasn't made lightly, but Thumbs Up/Down is integral for the future vision for Play Music and will be a central design point for our future releases."
Music isn't binary. Though the 5 Star rating system isn't terribly nuanced, many people relied on it.
If you want to bring it back, please sign the petition.
I love the player, but I couldn't care less about the subscription features. However, it works amazingly well to stream my own music, and I would like to keep rating it. The thumbs up/down sounds like a smart idea for the shuffled radio aspect, but not for my own personal library.