it looks good, but conceptually, the scope eye piece should be bigger, and not curved like that (its the front part wich should have that curving, so as to hide the lence from sunlight). the front lence should be way inside the scope to exclude bright off target light sources. the scope overall should be longer, the grenade launchere sort of thing (if that is the function) should not have such a thick wall on the barrel, or maybe even could have higher caliber for that matter.
Awesome. I love the look of it; I've never seen any of the StarCraft Ghost concept art, but I have seen a little of the stuff for the original StarCraft. I always loved the game, I remember hacking the game in ICE to give the ghost a 3 round burst... I also did that for the undeployed Siege Tank, for some reason that worked really well for them.