So Spotify is great, but I face a problem which I know has been asked before, but wanted to stress the issue again.
Spotify portable for USB
I think the whole point of portable software is the fact you don't have to install...I am at university which heavily denies you access to install software, and I flick between different computers throughout the day...I have began using Grooveshark to listen to music, but why should I use another service when I pay £9.99 for this one? Spotifty strives portability as one of their marketing ploys, yet because I don't have a fancy smartphone or tablet, I am eliminated from the service throughout the day...???
Might aswell use Grooveshark, which is browser based, but lose the stability of actual software.
As you can appreciate, spotify relies on a closed system in order to prevent piracy and make sure artists are paid for each track play fairly. That is why you can't use spotify on any device that does not support the spotify application.
Good news is, there is a Web browser based client currently in a closed beta test which should hopefully be released later this year!