This really isn't pixel art, it's just lineart, there's no color or anything, what are we supposed to critique on? He doesn't even have a
face, okay, well here's my attempt at critiquing it:
His stance is odd, especially when zoomed in, the overall person could be bigger, according to how his face is, he's looking right at the person, I'll assume this is just a stance, so you should work on that.
Since it's a platformer sprite, go look at other platformers, see how their sprites are done, go check out my "The Best Game in the Universe" thread, there's some good examples, since I'm awesome and all(The current version is only good for colors though, I'm making a new one that doesn't look so odd), Takam's Twinsen threads are also good examples, because you know, Takam makes some manly platformer sprites. One more thing, go here for some good tutorials:
http://www.wayofthepixel.net/pixelation/index.php?topic=3467.0