I have become a total Spotify addict. I have almost totally stopped downloading MP3s and am gradually locating all my favorite music on Spotify. I posed a couple of semi-sceptical notes when I first started using Spotify and so I am due for an update, right?
So what has happened since? I find that I am using Spotify on my iPhone and on my computer, all the time. Occasionally I will dip back into my large iTunes collection to remind me of artists that I want to listen to. But I promptly go onto Spotify, and search for the artist and grab all their albums not just the one or two I had in iTunes.
It turns out that for me, not 'owning' the mp3s is not a big deal at all. I am almost always online when I am playing music, either on a computer or an iPhone. And when I am not actually online (on a plane for example) it is easy to make selected play lists available on my iPhone as long as I thought of it ahead of time.
Comparing it to Rhapsody, they are very similar services. They cost the same and seem to have similar sized catalogs. At least, most of the music I want I can find on either one. Still somehow I found that I am using Spotify much more often than I used Rhapsody. Rhapsody does not have a 'real' mac application so you have to have it running in a browser window which can be a nuisance. Also the Spotify UI experience is a little more streamlined (although it misses some really important features that Rhapsody has.)
Comparing it to Pandora, the clear difference is that on Spotify you can play the specific album and/or track you want, over and over again if you want. On Pandora you can just ask for music that 'sounds like' another track. And while it does a decent job, you often want to listen specifically to Madeleine Peyroux and no one else.
Comparing it to iTunes, the clear difference is that I don't own any music. And if tomorrow Spotify goes out of business or I decide to stop subscribing, my whole 'collection' disappears. What I own is the list of music that I like, and presumably I would be able to move the list over to the next service. Also I am constantly discovering new music and so my iTunes collection has lots of stuff that I don't listen to anymore. On the other hand, lots of stuff, like NPR interviews, Technical podcasts, lecture series and other material is only available as mp3 and so I will keep using iTunes for that, I am sure.
What about the new integration with Facebook? Not sure yet. What music I listen to is no secret. But it is a little weird that people in my network can watch my listening habits, play by play as it were, and I listen to a lot of music. As soon as I wake up the music goes on.
Anyway, all in all, Spotify is great and is now my primary music service.