First, he conspired with people in the UK, to get the Canadian Constitution to Canada - for which there was absolutely no reason to except give the federal government a possible power to modify it, AND cause more pain to the Francophone population (as the charter was made after England's obtention of the lands after the Seven Years War. He also wasn't exactly a great economist, and somewhat antagonized Quebec simply because of the separatist movement.

And he was a bit full of himself.

THEN there's the conspiracy theories which may or may not be true, like that he was behind the FLQ (which was an extremist Quebec separationist group - which forced the military into the streets of the major cities). And that he was acting behind closed doors to increase the powers that a Prime Minster had (hence the Constitution patriation) to maybe take over Canada eventually, or at least set up the place so that it could be done by some party.

For me though, it's mostly the focus on "how to get things done" rather than "how to make a budget to get things done" that bothered me, but oh well.