I have used Toodledo every day for two years and it is great for GTD. I suggest the following enhancements that would make the IOS user interface more efficient.
In the Task Details view, move the Fields area to the top of the screen and show the list of Subtasks. Make the display scrollable to view all the Subtasks and Notes. This would avoid the need to click on Subtasks or Show All.
I have used the Toodledo IOS app and website for the past year and it is great! The large font size for tasks in version 3.0 was fine for me. However the font size on notes was too small. Version 2.x was better because I could select "bigger fonts". Can you continue to provide a font size selection for us "older folks"?