Disclaimer: I'm working on a productivity app.
Disclaimer: I'm working on a productivity app.
So from that perspective, I would say retention and engagement are low since not many are willing to put the time and effort to do that tool justice.
"Attach" means charging for something outside of the app store. Dropbox, Uber, Square all do it. I remember seeing a Chris Dixon post about this on HN a few months ago.
My take-away was that I wanted precise pointing and a keyboard and a big screen for those tasks, because I'm fussy about the results.
But like a lot of the HN audience, I'm not very typical, so my experience may mean little ;-).
Regarding payment model, payment wasn't the issue. It was functionality.
Turns out that to get the lines straight, group/ungroup objects, line everything up, choose fonts and colors, etc., etc., it takes a lot of input that is not particularly well-done using touch.