Spotify on CarPlay is buggy bordering on unusable. If I try to play my starred playlist, I just get a 'empty' looking playlist. Sometimes it will start playing something after 30 or so seconds but most of the time it does nothing.
Spotify will also randomly force close. Music cuts, screen goes back to the main carplay menu.
Sometimes it will startup normally but then I get no sound.
This is Spotify running on iOS 8.0.2 via iPhone 6+ on a Pioneer AVH-4000NEX head unit.
Please, please work on CarPlay.
Edit 1-5-2015: Spotify 184.108.40.2064 on iOS 8.1.2 (12B440) on iPhone 6+ and the issues are still there.
Edit: 6-11-2015: Spotify 220.127.116.114 on iOS 8.3 (12F70) on iPhone 6+: Recently I've had better luck with Spotify loading correctly and playing correctly. Occassionally I'll have audio break up (not sure if that's the iPhone 6+, Spotify or the head unit). It should be noted that I like Spotify and don't care for other products out there (for some reason another product was marked as the solution to this thread). I'm glad to see some positive movement for Spotify and CarPlay.
6-11-15 Update 2: 2 things happen frequently: Songs play at 2x (skipping every few seconds). Spotify stops responding for 4-5 seconds.