Spotify seems quite buggy at the moment. Better than nothing, but still needs a lot of improvements. Here are the things that don't work well yet (note that I have a paid subscription, not using Tesla's free account):
1. When switching media source using the right scroll wheel to Spotify, nothing happens.
2. When searching using voice commands, nothing happens (have to use the touch screen to go from "now playing" to "browse", then the search results show up.
3. Doesn't synch stations (if you have a paid Spotify subscriptions). But it synchs playlists, artists, and songs nicely.
4. Spotify kicks me out regularly (not every day, but at least once every 2 or 3 days)
Not really bugs, but improvement opportunities, compared to the iphone app:
1. When listening to stations, can't "like" or "dislike" songs to improve the station.
2. Since you can't "like", the playlist "liked from radio" doesn't get updated like it would from the iphone.
3. pressing the "+" sign when playing stations will simply add the song to my songs - I would then have to find it in another app and add it to whatever playlist I chose.
Like I said, better than nothing, but still lot's of possibilities to make the Spotify experience in a Tesla better than it is right now.
Model S 90D, titanium, delivered 10/28/2015.