In mobile ubiquitous computing environments, users will be able to interact with different devices, providing them with many services. The technological heterogeneity of these environments is expected to increase overall system complexity. Flexibility and adaptability thus become key requirements. The goal of the IST-Simplicity project is to design, develop and evaluate an architectural framework supporting easy customization of terminals, services and networks in a consistent manner. In this paper, we present results from focus groups that have provided valuable user feedback on the concepts, user scenarios and business models developed during the project.