Considering how absolutely terrible the native client is for Spotify I'm assuming a terminal client would just run rm -rf / or some other joyful error. I wouldn't trust anyone at the Spotify team to code...well really any user interface, GUI or otherwise.
What don't you like about the native client for Spotify? I (on OS X) find it quite nice, actually. (Maybe you're speaking of the Linux client, which I haven't used in a while.)
Not sure if it still works. If it does work it requires that your user is subscribed to Spotify Premium I believe.