This is really one of the best sketches I have seen in my life, the sheer complexity of this thing is amazing, plus the detailing makes it just perfect.
Personally I don't come anywhere near to your level so I can't really review it.
all in all it's really really amazing and your creativity is just incredible.

Wow. Um... *is speechless* Haha! Let me count the things I envy... xD
hah