The anatomy is pretty off, especially in the legs, along with what Different55 pointed out.
The pixels are different sizes. Some are wider, some are taller, some are both, some are neither. When uploading a small piece like yours, you shouldn't upload a zoomed-in version. PixelJoint has zoom-in-out buttons that preserve the quality of pixel art, and keep all pixel sizes even and pixel-y.
thanks, i'll take that into mind for next time! :)