Clear has one of the best-designed user interfaces I've ever encountered on the iPhone/iPad. It is the way apps should be. So simple and easy. I'm giving it 5 stars despite some shortcomings:

1. It would be nice to sync with the desktop (iCal?) and between devices.
2. It needs Reminders and Alerts (and Due Dates, etc.)
3. Some kind of support for longer notes. Right now, single-tapping an item lets you edit the item. Maybe double-tapping should let you open an item's "detail page" where you could enter the due date, add an alarm, or type a longer note. 
4. Also, sharing a list? It would be great if my wife and I could add to or just see each other's shopping lists. Though now, I admit this is "feature creep" that could detract from Clear's simplicity.