Well...
Your drawing is really good!
Ther's only one thing is making your drawing looking a little bit weird:
The left arm:
1- Hand is a little bit too big, compared to the other one.
2- Same thing for the arm in general
3- The position of his hand is disturbing me o_o I think you could make him hold it!
Otherwise, your drawing rocks! Effectively, the colours are smooth and nice to watch, the character is funny and scary at the same time and your sky is looking really great!
Nice job! ( You know, I'm not an artist , but I think you really got talent)
Friendly,
Rocket-Kid :D