When I say not a fan of the concept, I absolutely don't mean I disapprove. I don't have any problem with organisations raising money this way, nor with people choosing to donate money this way - I simply don't like donating myself.
Trying to chose between fighting HIV or starvation, cancer or... etc. etc. is hard enough. Looking at Watsi's homepage, does Chimwemwe from Malawi deserve my money more than Kirshan from Nepal? What about Lidiya from Malawi? I can see the point of view that it's nice to know your money has definitely made an impact on somebody's life, but personally I don't enjoy the burden of making that decision. I'd far rather be 0.0000000001% of a big solution than 100% of a small one when it comes to charitable donations.
All that said, the fact that I dislike it doesn't take anything away from my thinking that Watsi looks like a great site, my opinion doesn't change the fact that anyone raising money for good causes is great and if the method used here helps that then no complaints from me.