I've been using Greenlight, and long story short, it was awesome, until one of the kids tried to make a purchase. They didn't have enough funds, so Greenlight took money straight from my bank account, not the parent wallet, but my bank account, and put it into the child's card. So yes, it's very possible your child will try to make a purchase and even if there isn't enough money, Greenlight will snatch money out your bank account without you authorizing it! They say it's in their "cardholder agreement." Totally unacceptable! It defeats the purpose of having a parent funding wallet!
Bottom Line: No, I would not recommend this to a friend