It's hard to see how Madara managed to implant is Rinnegan into Nagato in the scene as it was shown to us.
Given that implanted eyes don't seem to be able to be turned off, it seems weird that Jiraiya never noticed he had them until that moment when he killed that ninja. Did he just ALWAYS have his hair over his eyes?
Which would almost be forgivable if he at least got some results.
Except every single one of these things he does ends up creating a super-powered monster that ends up making Kohona worse. So not only is he a terrible person, but he's terrible AT it.
He created Itachi, Sasuke, Kabuto, and now through Nagato, ALL of Akatsuki as an antagonistic organization.
At this point, I'm fully expecting whatever is going on with Rin to be his fault too. Some plan of his to weaken the Hidden Mist that backfired horribly. If I didn't know Madara was probably out of circulation before Danzou was even born, I'd probably think he was responsible for him as well.