Maybe a tad sparse but the HUD especially is great, most people seem to rush them these days, worth that effort. Some more background/foreground elements to better set the scene would be nice but a cool mockup all in all! The rocky floor is wonderful pixelling too!

The stuff you have looks good, It just seems a bit empty.

 This has a lot of potential to be a very good mock up. But it seems you rushed it a bit. I bet you probably wanted to do a bit more? Heck, I hate time constraints, but I'd like to see this finished or worked more on even if Secret Santa is finished. :)

 i like it but the shading on the tree is a bit funky :P 

 I LOVE THIS, very sweet style!!!

Hmm... to me this piece is quite "off". I like the character designs and the rock texture, but everything else fails. The atmosphere is too dense/dark/dull/foggy and that background doesnt seem well finished. There could be some trees and cliffs. The sky should be lighter and have some more clouds.

Those HUD elements are really nice, I forgot to mention. Meaby make those character picture outlines 2x.

Then theres the thing with the main idea of the picture. Why is a tree and some warrior fighting in the middle of nowhere? You should add some "base-type" structures behind the characters (and behind I mean left to the knight and right to the tree, not BEHIND literally...) 

I see a lot of flaws, but this picture has potential. Take my pointers and improve this piece. You could make it way better than it is now. I´ll give it a 4/6, but dont worry. Improve and I´`ll make it a 6/6 for sure... :P