I have to admit that Spotify is exactly what we had needed for years prior. Huge music collection, reasonable pricing, free alternative with non-over-the-top advertising, great audio quality, clients for all kinds of devices (phones, tablets, web, amplifiers) and works great with Firefox under Linux with no software required.
I have even noticed when I searched for a few albums that were missing over the last year.... they were eventually added. So they even seem responsive to what people are trying to find.
I will never stop relying on the old model of purchase/rip/local music. I like "owning" my collection and being completely non-dependent on the 'net. I have some older and obscure music that will NEVER show up on streaming. But that doesn't mean Spotify isn't a great augment to what I do/use; especially for music that I wouldn't otherwise buy. And more importantly, it is a great thing that I now recommend to all the non-technicals out there (and they WAY outnumber us). Regular people that just want a way to enjoy music without trying to understand or deal with ripping, proprietary music services like Apple's, or resorting to physical media. I am probably responsible for referring over 100 new Spotify customers a year through word-of mouth, demos, and friend-of-a-friend discovery. Two new customers just yesterday, as the sister of one of my friends complained to me that Apple revoked her ability to access the few dozens songs she bought from them (a story I have heard NUMEROUS times).
Pandora still has Spotify beat for just "radio station" type listening, even though their collection is much smaller. Even so, I have discovered lots of new music through Spotify with their recommendations. And that is something Spotify could improve- they need to allow users to directly rate songs (like Pandora does) so it can learn what we like and offer more recommendations. And the other is a better "radio station" type mode, like Pandora has.