It's good--lots of detail for a small canvas and only 4 colors. However, it's very bland. It's not engaging to look at whatsoever.
I suggest that you let each color....explode a little, you know? Make each color work for a living! Right now you got very unsaturated, faint colors, and they're all just barely hanging out together, like ghosts. Imagine if each color was bursting with power! I'm not saying be all out bright and happy-2d-platformer--lol, it's an ugly mayan warrior for god's sake
--no, not bright and happy, but a dynamic palette. (maybe let the blueish hue be the shade color, the red be the neutral, and the light-greenish hue be the highlights?)
Also, a few words on the outline: As it stands right now, you're using a lot of precious pixels with the black outline. If it were my piece, I'd maybe only outline just around the outside...and maybe use a few specks of black here and there for the really dark areas--the rest of the areas could be done with a dark color (see above
).
With these two things, you would be addressing the current lack of depth/volume...and thus make it a lot more fun to look at.
Good luck!
EDIT: btw, welcome to Pixelation!!