with premium account, if you have a sonos or squeezebox or modern network multimedia receiver (eg Onkyo), you can stream to your home music system.
Also with premium, can download to your phone, laptop, tablet and listen offline, and sync all the devices.
I like the popularity column as generally the better tracks are more popular so handy if you hear a track you like from an artist and want to hear more but want to avoid the dross.
And the best part is that with premium you can run spotify natively on linux. It was always a bit carp via wine.
Just a bit annoying that there is quite a bit of stuff not on Spotify - no Led Zep for instance. I can understand the big bands opting out because they can, but there is quite a lot of other stuff missing.