Really nice execution. I think that the core feature that is apparent when using the app (simplicity) is going to be one of the downsides of using it in a team based environment:
1)How do I know if someone on my team has completed a task, if you send out email notifications,I might as well use email.
2)How do I make the lists private to just my team?
3)How do I assign a todo or know who ticked that a todo has been done?
Its these sort of things i'd be looking for, but then you're left with another generic (if nice looking) team based todo list.