Sam, i aint used Spotify but i believe it allows the option to purchase music you like. Obviously this could then be played on a portable player. Effectively a try before you buy as it were.

Spotify is a streaming music service, much like Pandora. As yet there is no way of playing its music outside of Windows and Mac operating systems (although can run under Wine in Linux), let alone on network music players like Squeezebox and Sonos. And you certainly can't download tracks to an MP3 player.

I hate iTunes. A lot. But this is hardly a competitor when it's an entirely different product whose music can't be listened to on a portable MP3 player.