Awesome picture.
I've always been a fan of the JJA design.
The snow turtle's pretty awesome looking, especially - and you used a nice color palette all around. It's pleasing on the eyes, for sure.

One thing I would point out, though - Jazz has a good sense of motion in his body, but the snow turtle seems a tad rigid to be making such a swipe (especially in his legs|torso ratio).
Otherwise, absolutely no complaints.