@Benjiro: Mira algunas imágenes de referencia, el arma no es desproporcionada en relación con el carácter =]
Not bad, the face looks a bit flat though - the shading of the suit/body brings out the shape a lot better. Plus the hands and the gun seem a bit too big, but that may be just me 
Solid job, Neutral. Perhaps a bit stronger contrast of shadow to define the shape a bit better and create a deeper character.
The Gun looks a bit wonky.