I'm the last generation but I want to share my experiences too:
My mother is able to unlock the family iPads and maybe even my iPhone, she can open the mail app too and read the email on the current folder.
My father knows moderately well how to use his iPad 3, I just can't stand him when he uses it to take pictures.
My grandfather (very active businessman at over 75yo) knows how to handle his iPad 3, but he has no apps other than the default ones and two or three others. He also uses the back of his iPad to attach Post-Its, some of them with username and passwords (like the Apple login)
My mother is able to unlock the family iPads and maybe even my iPhone, she can open the mail app too and read the email on the current folder.
My father knows moderately well how to use his iPad 3, I just can't stand him when he uses it to take pictures.
My grandfather (very active businessman at over 75yo) knows how to handle his iPad 3, but he has no apps other than the default ones and two or three others. He also uses the back of his iPad to attach Post-Its, some of them with username and passwords (like the Apple login)