Felix Salmon reviews them:
[I]f you’re one of those extremely wealthy people who has pledged to give away most of their money, then follow the spirit of the pledge, rather than just the letter. It’s not enough to set up a foundation which will receive most of your wealth when you die: that’s, quite literally, a cop-out. Instead, embrace the concept of front-loading, and give the money away right now, as much as you can. In a world which is getting richer, your money is best put to use now, rather than in the future. And in a world with many vicious cycles, an increase in up-front investment can prevent enormous damage down the road. You’re not building a business with permanent equity capital, you’re trying to make a difference. And if you think that the world would be better off if you invested the money, made a huge return, and then gave away that much larger sum — well, that’s just your hubris at work.
Remember, in philanthropy, you’re meant to be the humble one. The graveyards are full of people who dreamed of giving away hypothetical future riches. Much better to give away real present ones.
Naturally, we should try to ensure that our charitable efforts are more rather than less effective, and poverty of the kind Singer focuses on is a quite proper object of charitable remedial effort. At the same time, I cannot see how to justify a principle which says in effect, 'Do no good for others unless that good is the best possible good you can do'. Not only is this impractical since you won't always know how to optimize your efforts, but it means you must override considerations like love, loyalty, gratitude, the spontaneous impulse to be helpful to proximate others, or others you just happen to know about, or others for whom you have some special sympathy (for whatever reason), and so on.