This stops working if you are in a team. I have one project that I work on by myself, and another that involves a small team. The first one is only pen and paper and some github issues, the other is using Github's project management features extensively and it would not work without something like this.

My writing is far too ugly for that. Also no grep. But I thought about one of those e-paper notepads thingies...

Only for personal use though. Any team of 2+ people will struggle to keep track of paper notes.

I did use paper and pen before but finally ended up with digital apps.