User involvement in the development of new products may offer a novel approach to improved methods of meeting customer needs. These users are considered to offer possibilities for generating original, valuable, and realizable ideas leading to successful innovation. However, the merit of users' ideas compared to ideas generated by the company itself has not been investigated empirically. In the present study, advanced users, ordinary users, and professional product developers were given the task of creating ideas for future mobile phone services. The main purpose was to examine the benefit of involving users in suggesting new product ideas in an innovation project. An experimental three-group design was used in order to assess the output in terms of its original, valuable, and realizable merit. The results indicated that ordinary users create significantly more original and valuable ideas than professional developers and advanced users. Professional developers and advanced users created more easily realizable ideas, and ordinary users created the most valuable ideas. The results were discussed from the viewpoint of divergent thinking. It was suggested that divergent thinking was facilitated through the opportunity to combine different information elements that appeared separate at the outset, such as personal needs coupled with the functionality of mobile phone services.