Amazon's streaming music competitor is awful. The apps are bad, the web UI is bad, the selection isn't as big, and the audio quality is middle-of-the-pack. In general, it's a "oh right, I have that Amazon service because I have Prime"; a similar comparison would be Prime Video to Netflix.

Spotify is better off in most ways (their desktop app still sucks, but the web UI is better).

I wouldn't judge a competitive threat solely on a V1 implementation, given it's from a company with engineering chops like Amazon.