It's a big discussion, GFAW. A lot of the criticism is based on that he is using his wealth to guide public policy - philanthrocapitalism is the catchword. Why should a programming billionaire influence vaccine usage in Africa, for example.
Also, buying global properties, farmland, yachts, private planes etc whilst preaching isn't going to go down well with anyone.
Is he generous? He's giving away money that he will never be able to spend himself. Surely someone giving their last spare $50 to charity is being more generous, according to biblical principles.
It doesn't keep me up at night, but the level of wealth that a relative handful of men have on the planet, is worrying for the future.
I enjoy travelling and no matter where you go there is evidence of the rich people of years ago, it maybe a stately home, a factory, a housing estate, a castle, a museum full of old things and such like. All things bought and built years ago that we can enjoy today. What lasting monuments are the rich of today leaving for future generations?