The orchestration is lovely as usual, and I like the themes. It has strong John Williams vibes.
I think the main area for improvement is creating a more believable accoustic space. Most instruments sound close-mic'd or modeled, and there's no reliable substitute for the sound of samples recorded in a hall. Close microphones capture more information from the instrument than distant mics, and it's this extra information that tells our ears that the instrument is right in front of us rather than on an orchestral stage in a nice hall. The drums are the worst offenders - they sound totally dry. I'm sure you can improve the sound with plug ins, but having a "wet" library would be much more effective.
Also be careful about repeated samples in quick succession - this can easily give your song a very mock-up-y sound. Sometimes it's unavoidable, but there are often workarounds.