Predictability
A good proxy of an interface's quality is how predictable it is for the user. This can be achieved with either a lot of text on top of each button or good visual language.
We got a special case of poor predictability with our command line because our reminder-setting system is based on processing natural language - not on clicking a bunch of buttons and date picker menus. Since there are so many ways to indicate the same day (tomorrow, in one day, April 14th) the system might 'misunderstand' you and miss the reminder date you aimed for (sometimes by weeks or months). Also, the system cuts the date/time data from the task text - so sometimes the wrong words get cut off. To make sure users don't shoot themselves in the foot in such a way, we've come up with a solution. Some javascript jiujitsu allows us to tell the user where the reminder will be put and which words will get cut - even before she hits the enter key. Here's what it looks like:PS. We're still working on the on-the-fly text coloring, but the reminder popup is already working on all accounts.
Posted by Dmitry Gorshkov

