Pros
Rewarding because you get to fundraise for a good cause and share facts and knowledge to those who aren't aware of some the things going around the world. You can meet people who are really cool just by yelling something at a stranger.
Cons
You have to canvass and persuade to strangers to pledge money to sponsor a child on the streets. Many people who stop either have something they're donating to already, will want to think about it, or hestitant about giving you card info even though you know you know you're working for a good cause, it can be discouraging and frustrating when people turn you down.