Abilty to add comments with ink editor.
When I review documents i often need to make comments/add questions to the author rather than edit the text with my own words. (Adding comments like: "Develop this argument", "Is this verified?" "Can we add information about xx in this section"). The ink editor is really easy to use but I lack this feature of commenting when using pen gestures. I imagine the gesture for that being a straight line from the text to the side of the document and a drawing canvas appearing to enter the comment in.