One way to measure the quality of a software system is to look at the size of its users' manual. The shorter the manual, the better the software. The use of well-designed software should be mostly self-evident. Unfortunately, too many software designers fashion themselves as experts in human interface design as well. The voluminous manuals that result are sufficient evidence that most interface designers are not as great as they proclaim.
Use standard interfaces. Use industry experts to design self-evident icons, commands, protocols, and user scenarios. And remember: Just because software developers "like" an interface, it doesn't mean that your customers will have any idea of how to use it. Many software developers like interfaces with built-in short-cuts. Usually, customers want simple, clean, clear interfaces - they don't want to learn tricks to enable short-cuts.
Reference:
Hoare, C.A.R., "Programming: Sorcery or Science?", IEEE Software, April 1984.
