This paper provides an empirical understanding of concerns that the application of a sensor-enhanced medical alert system, or personal emergency response (PER) system, raises from the perspective of care receivers (users) and care providers. Data were gathered in the context of a field trial of a PER system supporting both user-initiated alerts and automatic fall detection alerts. The system was tested at two residential care facilities for 3 weeks. Drawing on data primarily from post-trial group and pair interviews, we describe and compare care receivers' and providers' views on the following emerging concerns: (i) form factor and ergonomics, (ii) system feedback and user control and (iii) sensor precision and trust. Based on feedback from stakeholder groups, we discuss potential value biases, or discriminating factors, embedded in the evaluated PER system. We also discuss the implications of our findings for a value-driven design agenda for future PER systems.