Nice. This looks really good. The only thing that strikes me as odd, is how the nose, the wings and the engine seem very hard-edged, but the midsection seems very organic in contrast. But it doesn't take away from the design... maybe some hard edges along the body would tie it in. Might make it look even faster too...
Great work though.
"Your weapons are no match for ours! People of Mars, surrender!"
"Um, this isn't Mars. This is Earth."
"Earth? Earth-with-nuclear-weapons Earth?"
[long pause] "Friend!!"