Can't see the back, but one major thing I want to coment on is the two engine areas in the sides of the guns. It's fine BUT I would cut it back to where teh first part of the gun barrel ends.
Make it flat not pointed, and then recess it in to make an intake. I think it would look cooler that way.
One minor thing the guns could be replaced later on with slightly higer detail ones. (but that's a shallow cosmetic thing, I got a hangup with guns)

Also a tailfin over each of those 2 engine rectangular block areas could be nice.
Those are my suggestions. (for now). (save this version!)