Without seeing what you have, a general remark would be that everyone and his cousin has clocked at least some time developing at least one ToDo app. It's a right-of-passage thing for a lot of developers, just like a Weather app is the same for UX designer wannabies.
BTW, what set Wunderlist apart is not the features first and foremost, but their bold in-your-face marketing rooted in very pretty visuals and a fake arrogance routine. Whether they had proper hierarchies / first-class subtasks was quite secondary.