I upgraded to a Pro Account because of the Subtask Feature. Bit I find it a bit disappointing that the hierarchy Task-Subtask is broken in almost every view. Thats not what I expected: To have a intuitive way to organize tasks in hierarchies.
I like the way how it's done in Todoist where you can branch out almost infinitely.
So in order to see the task-subtask relation I have to click the Load Parent Icon and when I turn to another view the relation is invisible again.
Yes, this was done intentionally because if subtasks were always hidden below their parent, it would be likely that people would forget to do an important subtask because they didn't notice it. For example, if you went to the "due-date" view and clicked on the "today" tab, it is important that subtasks that are due today show up in there so that you remember to do them. If it was nested inside the parent, you may not notice that it is due.