Lately I use the calendar view a lot, it gives me a good impression on what is due on what date.
However, I think with a little addition it would be even more handy.
The addition would be a "Week view" button, which could be placed after the last day or before the first.
Clicking the button would give the same view as clicking on a day, but then applied to that week, ordered per day. So all due and completed tasks for that selected week would show up.