The whole Bill and Melinda Gates Foundation story is a mixed bag. On the one hand they've given away a pile of money, as much as some medium sized countries have given, to spread immunisation and other specific health concerns, they have their own agenda. There are curious links with the ultimate corporate evil giant Monsanto. The giving away of huge sums tends to lower criticism of the ability to gather such large sums in the first place.
Bill Gates' place in history is not entirely saint and not entirely sinner, but somewhere in between.