I like the platform. It probably works a bit better for kids who have a phone of their own, because they can use their device to track their own account. I don't love the fees, but I think if I had more than one kid I wouldn't mind so much because the fee would be split between different accounts (it's $4.99/month for up to 4 or 5 cards). I think Chase uses the same software for their kids' cards, so that's something to look into if you have a Chase checking account already.
That being said, as soon as my credit union will issue him a debit card at age 13, we'll switch to that.