I was about to do a fanart about Arms as well (but I want to draw Helix), in a short future... So.. is very cool to see that someone did it already, and very well done.

I think color choice could really expand this from an 8/10 to a 9. You start out with such good base colors and use a little variety in the spring with that red middle shade, but then don't repeat the effect anywhere else, for the most part. It's not necessary per-say, but unanimated, the piece would be so much interesting if it had some hue shifts weaved in nicely.

I am very envious of the proportioning and character control, though. Den outta den  

Amazing!