The UI is an integral part of how your application is experienced when
actually being used. To enable the best UX, base your design and
development decisions on the UI Philosophy of U.S.E.:

Useful - for the intended users and different situations, for
entertainment or productivity. Understand and respond to the most
important user needs.

Simple - to handle and easy to understand, engaging while not
interfering, helping the user to succeed. Support and enhance the
user's behavior.

Energized - experiences that make people smile, using the strengths
being on the move in unexpected ways. Innovate and add value, fun, and
energy to exceed the user's expectations.

Learn more about UI rules and components at
http://developer.sonyericsson.com/site/global/uistyleguide/p_stylegui...