Individuals experiencing various disabilities and aging who rely on Electric Powered Wheelchairs (EPW) for mobility assistance highlight the necessity of User-Centered Design in developing EPWs due to their diverse characteristics. This study evaluated the usability of a developed EPW, considering factors such as aging, prior EPW experience, and usage duration. Usability evaluations were conducted, including the System Usability Scale (SUS) and semi-structured interviews. Results indicate that elderly users rated the EPW more favorably than disabled users, with prior experience and usage duration influencing evaluations, suggesting a critical evaluation based on familiarity and robustness. Disabled users emphasized operational issues, especially regarding footrest height adjustment for long-term severe disability users, while elderly users appreciated its ease of operation. Longer EPW usage enhances user understanding, with previous device experience potentially influencing evaluations. These findings underscore the significance of considering user experience factors in EPW design for diverse user groups.