Change color of board, zoom, pen size
Your is app is fine. I use it on my iPad and am loving your app. Small improvements would be great:
1. Change color of background (to check due date at a glance a white or uniform background would be helpful).
2. More sizes for pen and eraser
3. Ability to zoom the board for bigger boards.
4. Date for repetitious tasks (like watering the flowers every monday)
But try to avoid higher complexity on the UI. Your low complexity is one of your USPs.
I vote for a couple of things on this post. I find plenty choices of pen size but none for the eraser. One touch will erase so much of your note that you have to re-write most (if not all) of the note. The zoom feature would also be very helpful. Otherwise I love the simplicity. I use it most because I can grab it and use it quickly. Thank you for a very cool app.