Well, he has killed many many brown people and helped sow the seeds of radical Islam which is a culture killer (especially if you are a female or like music or question anything you are told). He has had a chilling effect on journalism and on the transparent conduct of his own allegedly democratic nation.
He has, upon his request, had a law passed that allows him to imprison any American without due process indefinitely. Viper task forces manned by federal officers check Americans papers for no cause on federal highways. Immigration officers check Americans papers miles and miles away from any boarder with no cause. The government has the right to seize any electronic device within 100 miles of any boarder with no warrant or cause. Just a small sample of the ways he has degraded our nations constitution.
I'll agree that he doesn't rank with Hitler in body count or Stalin in destruction of religious institutions or Mao in destruction of cultural institutions but he is no saint.
I'm no rabid partisan. I voted for the guy the first time he ran. He is at least the worst American president in modern history.