Actually, I do appreciate the critiquing, Helm. Anyway, the image will stay as is (It was for a thread on Something Awful - Turn cartoon characters into monsters), but all the comments will be taken into consideration.
Extended arm is too short - Agreed, and I can't believe I didn't see it myself. As much as I complain about my lack of skill, things like that, I DO see, yet I didn't see it this time, and that pisses me off.
Bent arm can't bend that way - How so? The bent arm seems alright to me, but not having a source of reference for the pose, I'm open to any answer. The only thing I personally see that bugged me was the index finger is being shown from too much of a top view. And I would also try to elongate the arm a little bit, and get the elbow a bit more defined.
Unclean lineart - Don't exactly understand this comment. I'm assuming the "unclean lineart" comment is in reference to the style it was drawn in, but it'd seem odd for you to criticize the style I chose for the image. Only other thing I can think of would be you're commenting on how some details are undefined and hard to indentify (like the hand and cuff on the gun hand), which I'll again agree with.
Pose and frame - It was kind of the point for this piece. He's just supposed to be standing there and pointing his Zapper at you. I initially was thinking of a more dynamic, creature-esque pose, but I preferred the idea of it possessing a great deal of humanity - hence the upright position. Also, dynamic drawing, I'm not that great at. You're lucky I even drew the gun being pointed straight ahead.