Amongst many of the other things listed by others here, a big item for me is integrations between all your logged in devices. One killer example: I can listen

Amongst many of the other things listed by others here, a big item for me is integrations between all your logged in devices. One killer example: I can listen to a playlist through my ps4 while gaming (a unique feature in of itself), pull out my phone and pick another song in the playlist on my app. It tells me just below the play button where the music is currently streaming.