I think Ultron is a waste of time but thats just me. He needs more story time or something.
*Edited: Ultron is not a complete waste of time but make him more mainstream. Get a story going or have him assist some other villains. Seems like he's left out. He is suppose to be a big time Villain right? if so i don't know much about his power other than he's a team threat to Avengers. He can man handle Iron Man and Vision and kill them easily but i Mean so can Magneto and Dr. Doom.