Also see YouTube’s Music App Could Rule All Streaming Services (Wired) and a better-living-through-lowered-expectations case study in Amazon’s Streaming Music Aims for More Casual Listeners (NYT)
"On to the app itself, which you can download for free via Apple’s App Store or Google Play. YouTube Music is free, and doesn’t technically offer a standalone subscription service. But! People who subscribe to YouTube’s new $10-a-month YouTube Red service will get a different version of YouTube Music, which strips out ads and offers features like the ability to listen to music offline.
Does this confuse you? We can make it more confusing if you’d like: YouTube Red subscriptions also include subscriptions to Google Play Music, Google’s other music subscription service. Ah, Google. So Googley."YouTube Music Launches As Part of YouTube Red $10 Service | Re/code