Cool little guy. Simplistic, but at such a lows res, it's almost inevitable and helps kep things readable and clean.
Some crits:
The side view is on pixel shorter than the front, and the logo-y thing on the shirt is 2 pixels lower in the front view, which I assume wasn't intentional. Also, there're some weird things going on here by way of consistency. For example, the pants in the side view are outlined in dark blue, and the front (but not the back) of the shirt in dark red, while in the front view, both are outlined in pure black.
I'd listen to andy's suggestion and up the contrast in places, too. At 1x zoom, all the colours kind of blend togethre, making the image appear flat.
Good start, now keep at it!