Consequences of bad user interfaces
 

Bad interfaces may cause users to

• need more time for performing their tasks
• make more errors
• feel dissatisfied
• need more time for learning how to use the software
• not learn/use the full functionality of the software
• (if given a choice:) refrain from using the software

Good interface design therefore is important for any kind of interactive software, and of utmost importance in

• systems with high costs of failure (e.g., nuclear power plants)
• systems with high demands on operators (e.g., rescue coordination centers, combat aircraft, call centers)
• mission-critical systems (e.g., space mission control)