I downloaded this too and it is pretty damn good. I pretty much just use the player for movie viewing and winamp for audio purposes. After comparing the quality of the audio for both, I have to say that the media player sounds sharp, crisp and clean. Could be my imagination but I think it sounds a little better than winamp. But seriously, the sound difference is so minimal (if there is even one) that there is really no way to tell which is better...which is not a bad thing. They are both very good for mp3 playing.
9 does include a minimize to the system tray with a user interface complete with playlists and visuals so you don't have to have the program opened full on your desktop. That is a great addition.