That's how I usually know I've made a good song...
When I can listen to it for an hour straight and not be tired of it at that point, I know that the song will turn out excellent when it's finished. It was like that for the last 2 projects that I have done.
I like the expression on the instruments, it contributes to this beautiful feeling, not happiness, but determination and impending triumph.
One thing you could have done is pan some of the instruments away from each other so that each instrument sounds clearer. Many of the instruments are sitting in the middle of the stereo field, causing them to blend with each other a bit too much.
Excellent job, 9.3/10