Looks like he's doing a jig, or needs a wee, one or the other .
Seriously, the only crit I have is, why are there green pixels in his eyes?

You're free to decide that this double size is the way it's 'supposed to be', but the admins can also decide that this isn't going into the gallery because of that.
Although, to be honest, I think this is going to be rejected due to quality standards. Like you said, it's basic... but it's a bit too basic for my tastes. Simplicity can be great sometimes, but this could use some improvement, in the animation department in particular.

@daniel, Just because this site has special ways to zoom in on sprites, it doesn't that's the way it's supposed to be. Get your facts right, you don't know everything there is to know about spriting.

I don't care if this site can zoom in on sprites. Double sized pixels are the way it's supposed to be. You can't decide that, because you aren't the creator.

This ninja looks rather strange. His foot changes direction abruptly, and his other body parts don't move.

Oh, and is he jumping, or walking?

Actually, it's meant to be that way.