Hi Bob!
I've listened to the piece a few times over, and I've got some thoughts for you, as requested.
First off, the growth throughout the piece is very well executed; it builds steadily but with a good sense of subtlety, nothing too over-the-top. I really enjoyed your use of glockenspiel for those high accents, they really worked.
Your trumpet around 1:40 was bothersome, but I think that's more the result of the sample itself than the writing. The dissonances it leads into are very tense and then your little arpeggio-ostinato ending fade is a good transition. Having said that, I thought it did end rather abruptly.
Which leads me to my next point. The piece sounds more like a cue (as in film or game terms) than a standalone piece. The reason is largely because it doesn't do a whole lot to keep the attention of the audience on its own, and it has the short span that tends to signify such pieces. I think that this would work really really well as the musical track for a fantasy game's trailer, or perhaps for a dramatic in-game cinematic. I got a very clear sense of that kind of idea progression throughout.
In terms of orchestration, you didn't do anything too far out, but you are definitely competent with the arrangement you used. Again, I really liked the glock accents and I thought your use of the sections was solid, if a bit detached. What I mean is that they didn't really feel like the sections of the orchestra were communicating too much between each other; you gave them each a self-contained role and then stuck to it for the most part. That's not necessarily a problem, I'm just pointing it out.
The recording is well put together, and your samples do their job admirably with the possible exception of that trumpet which sounded a bit on the bitingly harsh side...maybe mix it lower and double it with some warmer instruments if you don't have another trumpet sample?
Anyhow, overall this was a really strong effort. Thanks for sharing and good luck with your composing. Let me know if you need me to take a look at anything else.