Sign up for it here:
https://www.amazon.com/music/unlimited?tag=imwan-20I've had the HD version of their streaming service for a while, and have been extremely pleased with it. (Click on the white menubar where it says "HD" to go the Amazon Music HD trial signup page ... the above link works for both the SD and HD versions of Amazon Music.)
The service is easy to hook up in multiple rooms. Good interface (much better than competitors) and controls. Sounds great ... the SD stuff is identical to CD quality and the HD stuff sounds like Blu-ray Audio, although there still isn't enough of the latter. Generally decodes well into Dolby surround (if you like that). I can't speak to the value of "carefully curated playlists" because I don't use them.
It's not a substitute for the full interactive listening experience (sitting down with physical media). I do love having my choice of music (not a DJ's) on demand in proper quality.