Any data on how this works for kids apps? It seems like there's something of a backlash against IAP for kids-targeted apps. Paid kids apps also have the benefit that parents pay when they install the app on the device -- rather than a pay prompt coming up while a child is playing the game, which would require them to seek out their parent(s) and have them enter their password.
It seems to me that it makes more sense to make app selection and payment be a single action at the point when the payer (the parent) is looking at your app, rather than at a later point when the user is a child.
When I give my iPad to my toddler, I disable purchases (among other features) so that this isn't an issue. It is quite annoying when kids apps have links to buy more stuff on them, but it seems so widespread as to be unavoidable. I guess I could just build my own :)
I even found a kids drawing app (explicitly marketed towards kids) on Android that had very adult advertising in it. That one got deleted, for sure.
It seems to me that it makes more sense to make app selection and payment be a single action at the point when the payer (the parent) is looking at your app, rather than at a later point when the user is a child.