I'm really digging this piece. The only thing I could think of is the transitions between the sections of the piece. I think if you could find a way to make them flow together more instead of going silent between them, it would help improve the overall flow of the piece. Also, the ending seems a bit abrupt. Other than that though, good show!
edit:
After listening to it again, I think I have a few things to add. The synthy part that kicks up around 1:35 is definately my favorite part of the piece. When you transition out of it at about 2:12, the section you transition into feels too short to me. I think (going back to my comments above) if you could figure out a way to blend that into the section that start at about 2:25, it would sound a lot better.
The section starting at about 4:10 is another part I really like. Listening to the sections between it and the earlier parts, I start to wonder if it all fits in with the overall feel of the piece. I think maybe some of the slower parts detract somewhat from the overall flow of the piece, so it might actually sound a bit better and to the point with them removed. I'm just conjecturing though, I wouldn't know for sure without hearing it that way. They might actually be necessary in order to pace the piece correctly. Either way, I think it might be worth trying out.