I've never heard anything bad about the Gates foundation for example.
Unusually for a charity founder, he has no need to make himself any more famous.
He is also, I am told by people I trust who've worked with him, always the brightest guy in the room, even rooms full of very bright people, but also is entirely free of ego. He expects people to be well prepared, but if they are well prepared and can show he's wrong, he listens, understands, and immediately switches to that position without any complaint. People who can switch position immediately based on evidence and argument are rare; most people hold onto their initial position because they aren't willing to admit they are wrong.
It was, incidentally, swapping that clarity for Ballmer's egotistical clinging to wrong positions that completely fucked Microsoft after Gate's departure ("There's no chance that the iPhone is going to get any significant market share. No chance.").