The ability to show nested subtasks in board view is great since it allows you to see how tasks are attached.
However, to complete a subtask, I have to open up the task and manually mark the subtask complete.
It would be faster to mark the subtask as complete from the main board view, just like a regular task.
As it is, waiting for the board item to open is so inefficient that I'm better off creating my subtasks as regular tasks and marking moving them off the board by marking them complete.