I think the only thing that bothers me about the Doc Ock picture is that he looks too short to me, and the tentacles should be longer. The Green Goblin's right arm also looks significantly smaller than his left. I know his left arm is somewhat flexed while his right isn't, but it still looks out of proportion to me. You did a great job overall though so don't take this as negative criticism or anything. I'm just pointing out somethings you can improve on in the future. I love that picture of just the Vulture though. I'd say you nailed him there.