again, he doesn't even how to properly shade an object, and you're telling him to AA? hey!
also, about the piece, does the ligth source comes from below? because that's the only reason i could figure by seeing how you shaded the tank. move it to WIP if you are planning to have some improvement on this.
Eeew, bad colors. Jaggy lines are bad, and need AA. I also don't like the sky, look up some examples of dithering in the gallery.
Take this to the WIP section of the forums, there are some great artists that can help you :)
I want to animate it...
...maybe later...
cool idea =)