I've been a premium subscriber to Spotify for 18 months and it has totally changed the way I feel about music: I don't care about owning it any more.
Back in the day, I used to buy a lot of CDs - probably 8 a month. It was a pretty hefty financial outlay and, to be honest, a pretty big waste of money. Very few CDs got more than a few listens and only the odd track here and there became a real favourite. Sometimes I felt I was only giving a CD repeat listens to justify the money spent.
With Spotify, I can listen to whatever I want, whenever I want. I can listen through the week's new releases on a Monday morning, check out stuff that gets good reviews when I stumble across them, listen to the whole of a track I heard a snippet of in an advert etc. Mostly, they get one listen and are forgotten but a few make it to a playlist and a few of those become proper favourites.
The cost is 10% of what I used to spend on CDs in a month and I listen to far more music than ever. Played through my hi-fi it sounds pretty indistinguishable from CD quality, it's easy to copy albums and playlists to my iPhone to carry around with me and it works abroad when I travel.
I just can't imagine going back to buying a couple of CDs or downloading 10 or so tracks from iTunes each month for the same money.