Show Subtask Count In Main View
Tasks can be seen listed in the main List view, however there is no way to know if a task contains any incomplete sub-tasks without expanding each task in turn. Given that there's so much spare screen real-estate in that main view, it would be good to show counts of # subtasks, # incomplete subtasks that are within each task - i.e. just an extra bit of text on each line next to the "Pin" and "Star" icons on the right-hand side.
There is a background progress bar that shows the percentage of the completed subtasks, but that's only available in the web user interface. I would love this to become part of the Mac app, and generally the native desktop and mobile apps.