I really love the tone of your voice and your range really shines in pieces like this. There aren't many that could do every part of harmonies. Your harmonies are practically spot on which is a hard feat for anyone. I think your voice really flourishes when singing harmonies. Are you in a choir or barbershop group or something similar? It seems that way.
I feel like your higher range when singing solo, specifically the "All is calm" sounds a little shaky and pitchy, so perhaps your higher range is something to work on controlling better! :) Also, take care when it comes to diction. For example, in the solo part, "all is bright". Take extra care to enunciate clearly as it sounds more like "all is bwight". It's not a huge thing, but just something that can become a little obvious, especially solo.
This is really quite something though and I'm certainly in the Christmas spirit now damn you heh! All the best :)