I agree that a real mobile version would be very nice. In the meantime if I want to quickly add a note to my Inbox/ folder I use the solution discussed here: Android share target - alternative implementation - #6 by schroederc
I create a icon on the home screen which pops up a textarea which I can type or speak into. Or it also creates a share target in Android which I can use say in Firefox to save a web page, etc. Not sure how this would be done on iOS.