I've been using your product every day for two years, love it! But like anything, there is room for improvement.

1. Allow the user to add custom pen/color combinations in the top. Example, I could have a red 5 mm pen button, a blue 3mm pen button and a yellow 5 mm highlighter. One press to change from one to the other.
2. Allow the user to do the same but with shapes and specific colors. A button for a red circle, and a button for a green square.
3. Add a quick button that will temp ignore fingers and palms so the user can easily make fine edits using a pen. Obviously this is aimed towards users who have a tablet that comes with a pen such as the S-Pen from Samsung.
   
4. A feature to allow a user to easily add a stamp or overlay. Currently I add a date/review/signature stamp using an image that I custom made with a transparent background using the 'add image' tool. Would be nice to have a single button to allow an instant insertion of a stamp or overlay.

That's it for now. Great product. Please continue to back it better!