[spdustin]

Looks like Paper, by FiftyThree:

https://appsto.re/us/KfqkE.i

[martinkl]

Correct. If you're going to try it, I recommend getting a stylus for your iPad, since handwriting with your fingertip doesn't work very well.

[spdustin]

Pencil (by FiftyThree) works great, of course. And unlocks the additional features in the Paper app. I'm actually quite impressed by how well it works.

http://www.fiftythree.com/pencil