I'm considering it, particularly as a way of introducing my children to world inequality in a graspable and hopefully not too overwhelming and depressing way. Daniel has shown quite a lot of interest and concern around the latest Action Aid commercial which shows a 5 year old girl living in an Indian slum. I think it might also spur me on into taking more action generally - keeping abreast of international developments; writing protest letters etc. just because it's much easier to get motivated when faced with a single human face than a bunch of statistics.
However, I also have some reservations - obviously it incurs more admin costs than giving direct to a charity and letting them spend it as they like, but I'm also worried about whether it is essentially treating a child as a form of entertainment in a way that does more harm than good.
Also, are there any significant differences between the different organisations that offer this and their approaches? I'll do my own research of course, but if anyone knows of any examples of particularly good (or bad) practice, that would be helpful.