It's quite good.
However, I personally think you should make part E more interesting and diverse by changing it into a more imitative part. In this part you do not use the full potential of an orchestra as you sometimes have half of your orchestra playing exactly the same drum-like theme. If played in reallife this drum-like theme would totally drown the more important melody.
I understand that the mentioned drum-like theme is very important for the piece, but you could give some of these instruments imitatives in connection with the more melody-carrying instruments of the orchestra. You wouldn't need to change the drum-motive at all, but could always give one of the brass/woodwind-parts playing the drum-theme at the time an imitative score beginning at measure 37 (I do not really know how to express my thoughts in English right now, I hope you understand what I mean).
You are currently using each instrument as one part without actually splitting them up into their own parts. However, remember that each orchestra has multiple people playing the same instrument - so you can have these people palying different melodies. You should really change how you use these people! Otherwise you do not use the orchestra at all but have a rather piano-styled arrangement that could be played with two people per instrument.
But it's good, I really like the theme!