The wonderful Smashing Magazine just posted a great article on “iPhone Apps Design Mistakes” but all of what they say can be applied directly to any mobile app, not just iPhone apps:
Designing a great app isn’t a simple task. Jacob Nielsen recently asserted that “the mobile user experience is still miserable.” Extracting user insights from testing is a challenge. People have difficulty telling you what they want; they usually only know it when they see it. But developers don’t have to tackle user research alone. Interaction designers are trained to find relevant user groups, talk to customers and read between the lines. They understand how real-world context affects an application’s design.
It takes a lot of leg work, but your efforts to understand user needs will be rewarded. The forefront of mobile technology is an exciting place to be.