Features of a Good User Interface

• Commands should be easy to learn.
• Allow the user to change his/her mind.
• The interface should be predictable.
• There should be fast short-cuts for more experienced users.
• The interface should prevent user errors.
• You should be able to safely quit at any time.
• Error messages should be helpful.
• There should be on-line help and "wizards" to help with complex tasks.
• The interface should be fun, not intimidating.
• The program should be "robust" (hard to crash).
• The program should offer immediate gratification.(Ted Nelson)
• Difficult tasks should be retroactively obvious.(Ted Nelson)