i thought i would contribute a little of my thoughts on it....
i think you have a great base and many of the forms and shapes are great. WIthout getting into all the things that make it work, all i think it really needs to some more attention to the lighting. Hitting some areas with hot spots, accentuating areas of color and light ie. the boosters and lighting. I think it could aslo use some reinforced silohuette value as well.
Cheers for a great peice in the works.
my 2 cents-