I think it's on par with built-in Spotify, and I suspect (though I don't know for sure) it's bandwidth-limited. I have both Spotify and Apple Music, and I have them both set to max quality / lossless on my phone app. I only had about an hour to try it out yesterday, but my ears are telling me the quality is better via the phone vs the built-in app (though the UX is far more convenient on the Big Screen, and with material such as podcasts, you'll probably never notice a quality difference). That said: it was trivial to set up Apple Music: aim phone at QR Code, accept access authorization, and done.