Ease of use has always been central to a great UI design, but what “ease of use” means, how it is implemented, and who needs to implement it evolve over time. Some think business and consumer application UI designs necessarily differ, while others think they are converging.

“Usability has expanded to things that are not as well defined and measurable like ‘appeal,’ ” said Tobias Komischke, director of user experience at Infragistics.

While it is possible to measure how much time it takes to complete a task, it is more difficult to accurately gauge users’ emotional responses to a UI’s color scheme, aesthetics and the perceived value of the application.

“Rich interactivity goes beyond look,” said Komischke. “The feel of richness is not addressed by the old philosophy, which is hard on developers because aesthetics are hard to define. You need [the] specialized skills of a visual designer and interactive designers who understand the input/output relationships.”

According to Rich Dudley, technical evangelist at ComponentOne, modern UIs feature clean layouts, smooth rounding, and simple glyphs that guide and enlighten the user. 3D effects are also gaining popularity.

“Controls and content should be logically grouped and neatly arranged, and text should be very readable,” he said.

The idea is to create applications that are easy to use, intuitive and immersive, so consumers and business users will remain engaged with them.

“Users have short attention spans, so you have to present lots of information quickly and allow them to drill down. Otherwise, they won’t pay attention,” said Julian Bucknall, CTO of Developer Express. “Long lists of numbers and text are not great.”