A little too much variety
The beginning was well done until the instrument from the right came in. You made that the focus, and anything focused should be in the middle. Also the bass was a little too high for the percussion.
The violins, piano, and the soft sound starting the song were all done very well. I think you just need practice pacing the song (not changing the instruments so often) and not changing the focus so dramatically (going from soft strings to the loud right strings).