Well done, though not entirely perfect. The song didn't really develop much and felt static to the point where it would have been overly repetitive, but you managed to work around that by changing up the beat midway and keeping the song at a short length. I feel like you should've put more into this song; you should've had it go somewhere - added more melody, dramatic buildups, and transitions into more parts to give it motion to develop it into a full song (though for background music, it does very well). The mixing/mastering was nearly spot-on - I'd suggest boosting the volume and the reverb on the piano a tad.
Please contact me if you would like to use this in a project. We can discuss the details.