I'm genuinely surprised at all the disdain for it here. Coming at least from Spotify's scattershot mobile UI, Apple Music is straightforward, consistent, and, critically, performant (Spotify is the slowest-loading, non-game app on my phone).
Certainly there are gaps, particularly when it comes to sorting. But all this about bold fonts and button sizes seems to stem more from an expectation that a music app should be a dense, text-focused experience like iOS's email app than from any fundamental design issue. Given Apple Music's focus on album art as the primary identifier for recordings, the UI has an appropriate information density - one can argue that's the wrong priority, but if you accept that premise, the UI supports it well.
