sweet but

next time draw a whole robot,not saying this is bad just a suggestion

Nice, is this from Eva?... I forget...

I really like the shading and execution. Furthermore, the shading really compliments the contours of the robots' armor. It's a little simplistic though for something intended to be so huge, try adding more detail, even if it isn't in the anime/manga series it would help especially when drawing a small part of the entire thing.