It's been years since I used iTunes on Windows but at the time incredibly slow and clunky to the point of incompetence would have summed up my views on it. I wonder how it compares now to Spotify there.

On another note, Apple have a pretty good story with Airplay - does Spotify on iOS support that fully? On Android they don't support Chromecast and I've always thought that was an advantage of Play Music over Spotify - maybe there's an analogous situation on iOS?