I really like the sub-tasks feature. I thought that I would be disappointed with the lack of only 1 depth, but so far its working very good.
However, what I dont like is that I have to always click Toggle Sub-tasks to get my tasks to show in hierarchy mode every time I switch a view. It seems to me that this should be the default. What is the point of using of subtasks if you have to toggle them on. Maybe this could be a user selected option?