yeah i'm gonna have to second what dhsu said about working on transitions and elaboration...
also much of what you have here sounds rather fake in terms of sequencing, rather rigid performance. the whole thing could use humanization both for rhythm and velocities (velocities aren't as bad though). vary the velocities and try nudging the place where the notes start off the beat ever so slightly...so it's not so machine like.
percussion is kinda exposed a bit, very much in front of the orchestra. in an orchestra context, you'll usually find them in the back...try to see if you can push them back in the space you've created with the reverb.
contrabasson sample at 4:07 is very exposed solo...add something else there too.
there's a lot of good things you have going on here, the issue is the production(realism) and the transitions.