I like that you can see all your tasks in one place, it's easy to check who is working on what task at any given moment.
It would be great if it was possible to add comments to each task or comment as part of the task creation process - this way we could communicate with our team members about their work without having to go back into email threads later. We use iplan for managing projects internally. This makes it really easy to keep track of everything going on within an internal department (we have over 100 employees).