It's not great for playing music if you're on Sonos, especially if you have multiple systems associated with a single account. The skill it integrates it to the speakers deauthorizes after some time, but instead of failing when you ask Alexa to play music, it acknowledges your request (Playing "whatever" on $MUSIC_SERVICE) and proceeds to play nothing.

Personally, I think they'll move some of the Alexa+ functionality to prime subscribers and increase the prime rate again to subsidize.

It's not free though. They are collecting a massive amount of data on you, and exposing you to liability as well with recordings kept on file. If you don't value your personal data then I guess it's "free".