The +'s:
Some very nice chords, and interesting ideas.
Love the sudden pizzicato section.
Great counterpoint.
The -'s:
You kind of get in to this rut where you repeat the same rhythm over and over, and it gets a little stale.
It's VERY 4/4. Try to spice it up a bit. Mix in some triplets, or syncopation. It might help it flow a little better.
It's one continuous tempo. Maybe throw in some dramatic ritards? Or, hell, if you wanted to get really crazy, try accelerating the tempo when you're doing those runs at 2:54, and slow it down at the climax. Basically, play with tempo, it will add emotion.
Maybe it isn't what you're going for, or maybe you feel the piece doesn't call for it, but... maybe work on melody a bit more. You have some great interplay with the voices, and wonderful counterpoint, but I never really felt as though there was a real melody or "theme" emerging from the piece. Maybe try writing a melody that works over top of what you have, play it once, early, then expand on it (play it again, and make it longer), and then do the pizzicato and run thing, and bring it back (in short form) again at the end? Just a thought.