Ok, let's start.
I'm gonna sort it in 3 categories so I'm not gonna get lost when I describe what I see, ok?
1. How it looks
2. How you use it.
3. Overall summary.
1. We have a big gun here. A handgun, yet just by the grim you feel that this is not a light one. Heavy and maybe slow, but you are sure that when you pull the trigger - nothing gonna stop it. Good colors, even the teal is not bad here. Would be cool to know more about it - what type of ammo it uses, can you shoot lasers with it? Of course, all shadows are whey they should be - not even one of them misused, and that's something I like. Very much. Don't know what to do with the user interface there. I assume you use it to see how much battery life you got there, or maybe even to calculate trajectory or possible penetration. Like on ammo, we need more info on it to follow.
2. The concept is simple. You load the battery clip, you aim, see what you got on the interface panel, adjust and pull the trigger. Then you see hell loose on the end of the barrel. Its a gun, so I assume you have some sort of bag to carry extra "magazines" and a scabbard for it too. A small rail gun - lots of power that comes in a handy way. Good.
3. Well, I can imagine a cop with it, I can imagine a crooked yakuza with it, and I can imagine a cyberpunk Dirty Harry with it so the image is good. The concept is simple yet futuristic to the bone in a pleasant way. The shape is normal(more or less - yes, I look on you, second barrel ._.) and still, you see the future in it. A single idea merged with a simple design, giving a complex and beautiful ending. I'm happy that I can create a critique of this one.