Did not expect the synths but they were a really nice surprise! I also dig the prominent use of the cellos.
A few things I have to remark upon: The key changes, to me sound a bit unconvincing - very sudden key changes are certainly possible, but I think somewhat smoother voice leading (preferably with some contrary motion! really helps in these cases) would make them more musical.
I felt the track lost pace towards the end of the cello/synth section, after that it kept things going nicely.
One last thing - to get that really sweet heroic, fanfaric feel out of your brass parts, I'd look at your two-part writing somewhat (looking up horn fifths might be helpful!) and perhaps look at a couple of classical examples (i.e. "Alla Hornpipe" from Handel's water music") - for example at 2:00, highest notes of the horn/trumpet duet, the 4th between the parts stand out pretty badly.
Anyway great tune!