Hey man, good work so far. Only thing I'd say is that for the length there is not enough done with the orchestration to keep a listener's interest level high. You have a lot of material to work with so try using the instrumentation to add interest in reoccuring parts.
Think of everything in choirs. Piccolo, Flts and Al. Flutes as it's own complete unit within the orchestra. Same with the Clarinets and Bass Cl., the Oboes and Eng. Horn. the Brass section (even within the brass the horns could be their own choir). If you think about it that way then you can reuse material utilizing one or two of the choirs and having the rest, well, rest haha.
The only thing I'd suggest as far as the score goes is that you need more articulation in the parts. What we hear in the mp3 is more articulate than what's on the score, and even if you are not going to have this played live right now, you should get in the habbit of writing everything as if it will be. Ask yourself "If I showed this to an ensemble, how many questions would I get?" you want to answer as many questions only using the score as possible.
Either way good stuff, will be following you on soundcloud!
Edit: One more thing. Violas are always in the tenor clef, even in score form. Also, to help balance out the brass section you might want to consider adding in a second Flute, Oboe and Clarinet, those tutti sections would be mostly brass otherwise.