If I were to make one suggestion it would be to have more light on the gun. I know what it is but it is not well defined in the picture. I do like the moody lighting and it fits this type of image.
Gun needs more light and your face could be just lit a little more. Would like to see a cookie on the background to break things up a bit too. Do Over!
I'd use a snoot on low powered light to highlight the tip of the barrel as the "business end" of the gun and keep everything else the same. I love the muted background. Nice expression that really carries the unnerving feel of the capture.
Do a yin/yang with your lighting from his face to the gun. Keep his camera left face lit, but then light the right side of the gun and a slightly more forward angle (so that the barrel and his finger placement is emphasized), with also a bit of light bleed into the shaded right eye for a sinister feel.
If the gun is a fake (not a metal) then watch your lighting for any give-aways, I'm sure there are a few tricks in CS3 that could punch that up for you.
I like that the one eye attracts my view and then leads to the gun however I wonder what it would look like with a little more light on the dark side of the face so its not completely black. Fun shot though and good expression
I like the mood and expression. I think the hand has way too much light on it as its the brightest thing in the photo. As long as we can tell it's a gun, it doesn't have to be lit like a product shot. Maybe shrink the glow of light in the BG about 30%
I agree with the comments about more light on the muzzle of the automatic. Your facial expression doesn't look very threatening to me like I'm about to be shot.
