So much potential, so much wasted. It looks way over sharpened, but it has a nice feel of depth. The colour blend is quite nice as well, but for some reason it also looks lsightly monotone. The black in the top right corner just looks like an obstacle, and needs to be removed, it's directing attention away from the focus point. Effects around the gunfire are nice but are a bit overkill, tone them down a bit, give it a more simplistic, and real feel to the piece to make it look nice. Left of the Crysis render also looks a bit plain and rushed, the background of that section just looks random and unfitting to the piece. Should have carried on with the more explosive abstract pattern you have on the rest of the sig.
Sigs are meant to be improved on, and this one definately should be, it's a great starting piece, with a bit of work it could be a masterpiece.