The use of sub-tasks in the Android app has been a very painful experience for me to test, with several showstopper bugs, out of which the following two stand out most:
1.
I create a new task in the Windows client, and sync it over to the Android app through a Toodledo Pro account. The task now rather shows up as three independent tasks in the Android app, i.e. the sub task connections are lost. A moment later (and possibly after some re-syncs), the sub tasks appear after all in the Android client, but the separate previous stand-alone copies of them are still there, and to make matters even worse, they are then synced back into the Windows client, so that it also has this dupe setup with both sub-tasks and dissociated task dupes.
2.
I use the Due Today 4x2 widget on my Nexus 4 Android phone. In this example, the above mentioned task with two sub tasks is in the top of that widget (the sub tasks being displayed correct, and the dissociated dupes removed by me by then). I then add a new task simple in the Windows client (having a short note, if that'd matter), and it is synced over to the Android client (again, through Toodledo Pro), and placed at the top of the widget due to its high priority. The previous parent task that used to be at the top of that list is now displayed as a subtask of the just added new task (which in reality has now subtasks at all), at the same level as its own subtasks, now rather appearing as three sibling sub-tasks of the new task. To make matters even worse, there's no way to "refresh" the widget, so I'm now stuck with this erroneous display of my tasks, making the widget both frustrating and quite useless. :-(
I really want to use this program because it seems so nicely structured and good looking (and I love having both an Android and a Windows client), but sadly there's just bugs and crashes appearing more or less wherever I click in it. :-(
