There's a growing interest towards human-robot interaction (HRI) as an area of research within human-computer interaction (HCI). Although nowadays robotics studies provide enough knowledge on social robots in major settings, there are still a limited number of studies that investigate expectations, attitudes and behaviors towards humanoid robots in the area of HRI. This study aims to investigate the older adults' perceptions and preferences of a humanoid robot appearance, which is planned to assist in healthcare activities. The preferences and the perceptions of a sample of 6 older adults are assessed through semi-structured in-depth interviews. By adopting a user-centered design process through the execution of techniques such as persona and user journeys, two different appearances are designed for the assessment: A cartoon-like, simplistic face with no specific gender and a more realistic feminine illustrative face. Findings support the notion that perceptions evoked in the users would depend on the human likeness of the robot's face. However, gender stereotypes also had impact on the perception and preference of the humanoid faces. A majority of older adults preferred a female human appearance for the robot by referring both to the human likeness and to the task of healthcare. The participants were able to understand the basic facial gestures in both appearances. However, they could not achieve to interpret the intensity of emotions in the expressions. In this context, when compared, simple cartoon-like faces seemed more affective to support detailed understanding of the expressions. Besides, the findings revealed that experience with technology and culture-specific aspects could also affect the perception of robot technology.