Okay the first obvious thing that stands out to me is that you have an arm that looks like a box, either you've made the upper section incredibly and abnormally large or you have forgotten to show the joint and beef the arm out correctly, I'll draw an example ASAP and edit this post and add it in for you.
The second thing is the eyes, I personally think they are too close to the edges of the face, but I could be wrong, wait to see if anybody else says the same thing is what I would suggest.
Lastly the pose looks as if it's being drawn 3/4, if this is the case the face looks off again, it looks like its looking straight at us but the features have been moved to the side. If this pose is in fact straight forward then I think your problem lies with the way you've drawn the chin... It's hard to explain why though :/
Edit: Never mind I think it's because the head is tilted slightly up if that makes sense