I don't want to suggest that this has not been a good thing overall, but donations of this sort are a highly political act, and can't escape being in spite of any intention.

An interesting (I found) examination of the the effects of such a volume of donation coming from a single organisation can be found here:

http://newint.org/features/2012/04/01/bill-gates-charitable-...

Again, not saying it's not a net good, just that it's perhaps not a perfect model to pursue either.