Three prototypes of shopping websites were evaluated regarding their perceived utility. These prototypes varied with respect to their functionality, that is, the influence users had on how product information was displayed. Overall, people were most satisfied with the prototypes of high and medium functionality, and the least functional prototype received considerably worse ratings. The high functionality prototype was rated best regarding ease of eliminating and comparing alternatives but worst regarding understandability and ease of use. We conclude that consumers appreciate some functionality, but only as long as such a decision support system is easy to understand without instruction.