Due lets you type "Make dinner reservation at 9am tomorrow" and your reminder is set for 9 AM tomorrow. "Cancel subscription in 1 month" and you get a buzz a month later. Just tell Due in your own words what you'd like to do, and when you'd like to be reminded.
There are no awkward date pickers to fight with, nor rigid date and time format to follow. Your reminder is set as soon as you're done typing. Due makes sure things actually get done by keeping you on your toes, sending you periodic reminders until you actually mark the reminders complete.