Personally, I like this piece a lot. Then again, I'm easy to impress in terms of pixel art. Everyone else here'll probably razz on you. Only thing I can see about it is lack of shading. Other's probably have a whole different tune, though.

I shoudn't be one to critque, but the pose just looks off. The left arm doesn't look right, like it'sbending the wrong way slightly. The right hand seems bent oddly, and...methinks the right pant (I'm speaking as looking at him, not facing the same way...I'm referring to the frontmost leg) seems a little too wide compared to the left. Also, the forward foot's off. I can't tag how, but it is to me.

...Then again, this is practically my first critque, so...heck, I might be wrong about everything.

...Like this?