The RoboCare Domestic Environment (RDE) is the result of a three year project aimed at developing cognitive support technology for elderly people. Specifically, the domestic environment is equipped with sensors, intelligent software components and devices which cooperate to provide cognitive support to the assisted person. The RoboCare interaction capabilities have been concentrated in a robotic mediator that acts as the main communication channel between the users and the intelligent domestic environment. This paper presents an evaluation of elder perceptions of assistive robots and smart domestic environments. Results show how the acceptability of robotic devices in home settings does not depend only on the practical benefits they can provide, but also on complex relationships between the cognitive, affective and emotional components of an individual's images of robots. Specifically, we analyzed a number of evaluation criteria related to the robot's appearance, the way in which it communicates with the user, and the perceived usefulness of its support services. Among these criteria, the paper proposes and reports an evaluation of the Proactive interaction modality (where the system takes the initiative) and On-demand interaction (in which the user explicitly requests a service). Users reported the On-demand support services in personal safety scenarios as particularly useful, but less useful in situations which are not critical. The paper also provides a discussion which can be useful for the design of future assistive agents and socially interactive robotic.