Lookin' gooood brutha.

lol.

I like it, but I would suggest maybe messing with the book he's clutching on to. I know you probably wanted to convey what he is holding, but the angle of it looks unnatural. (it's almost like he's about to drop it and is holding it to his leg)

his head is also looking a tiny bit squarish (but not by much!), you might want to remove a single pixel on the right side somewhere either at the top of the hair or just where the forehead ends.

Other than that, you've still got a solid black outline. which is fine for what it is, but you might want to consider colouring the outlines and experiment a little.

But that's probably a matter of opinion so don't worry too much about it.

Good job. =)