By no means bad, but shy of 'epic'
I really love the start, the tension building - but then in the middle it gets a bit too slow, then grows faster, and then slows down again for end and that really turns down the 'epic' meter.
I think starting off slowly, and then ending with hard drums/bass (as stated previously) ould make it much more 'epic' (alike the most notable trailer song used - Clint Mansell's Requiem of a Dream Remix).
Try watching already released trailers and create music for those trailers. I think it may help with the structure a bit if you're really aiming for it to be epic. other than that, it's great, but nothing I would associate with a Hollywood blockbuster trailer (more so the lesser financed Hollywood films).