I gave a windows 7 netbook to my grandma a few years back. It wasnt super bad, but eventually her eyesight started to ler her down. She upgraded to an android tablet, which is greatly helped.

She was fairly technically proficient though, she used to take the bus to the library just so she could take classes on how to use computers, so she set herself up for success there.

She is still mentally capable, but alas her eyesight is letting her down :(