Comment by yeukhon

I think the main reason for the success is that it's simple to use. All the hard technical work getting books and getting things fixed and updated are done by the grandsons. This is good because now the grandsons really have a reason to visit (OP doesn't even need to come up with a reason and I respect that, but in some other people's cases they simply need A REASON to do so).

It is a win-win situation.