Irrelevant, irritating, LOUD ads played in between movements of a single piece that are tied together. It's really irritating to be listening to something and have Spotify suddenly SCREAM at me the lyrics to some country song about taking my clothes off that I would NEVER be interested in, which Spotify would know if they could be bothered to look at my listening history, or even my last.fm account, both of which they can see. That said, I still use it to listen to music I haven't yet purchased.
I'm amazed how stupid spotify's (and all other free music services') ads are. Haven't they heard of contextual advertising? I'm listening to Kings of Leon, sell me KoL t-shirts, have them talk about their gold plated vinyl record, sell me wristbands with their lyrics on them. Nooooooooo, here's Rihanna's latest single. Enjoy!
It's like no one told them you don't have to exactly copy the old school radio advertising model.
I have no problem paying with my time. I just wish they would have me pay with my time by listening to stuff I don't despise with a passion normally reserved for Hell and all Montagues.
My breaking point is that their library doesn't have the music I want to listen to. I own a lot of Rammstein albums, and if I can't have those on my mobile playlist, I'm not going to bother.
(Yes, I can have it pull music from iTunes, but then I'm having to manage two separate libraries, one of which could disappear overnight as a result of a court ruling. The odds of that happening are greater than all of my backups suddenly vanishing.)
This. This is exactly why I do not ever use Spotify. Ever. I downloaded it, installed it, then noticed I needed a Facebook account and never looked back.