Thoughts on Ultron?

I thought Ultron had some potential, but overall came out to a weak, lower tier villain, especially when you consider he's an Avengers threat.

For starters, I think his mouth-breathing Decepticon design was bad. Marvel should have stuck the original design, and went off of that, instead of making a ridiculous-looking character. His design was also pretty boring, as Nando vs Movies puts it, he was just another Big Grey Villain. Granted, he didn't have a lot of colour in his original design either, but that would have been an opportunity to improve on (also Ultron Prime is golden in coloured)

His personality should have been less comedic. He's a robot that wanted to kill 7 billion+ people, he shouldn't be cracking so many jokes. Even Loki took himself more seriously, and he's the god of mischief.

His motive should have been a bit clearer. I didn't really understand what he wanted. He wanted to drop a meteor on the Earth because... humans were weak? they needed to evolve? They should have just stuck with his "Turn Earth into Robotropolis" motive, which they did briefly mention at one point towards the end.

Thoughts?