I'm a newbie who's never made a full piece myself, so take my advice with a grain of salt, but...
I really like your instrumentation and I think you've filled your soundscape very well. To make it even better, I feel like the biggest thing you could do is make your voices evolve more. While the balance of voices changes a lot throughout as the melody does, it feels more repetitive than it would otherwise because you reuse voices a lot (for example, it sounds to me like your different leads throughout the song are very similar). In particular, I feel like the beginning could use some of this as it feels very abrupt to me. The buildup into the main melody would also be a lot stronger if the instruments themselves evolved alongside the instrumentation.
But again, great work!