My mom is pretty good too, she is in her 80's, attached to an O2 tank full time and can only get around with the help of her walker, but her mind is still pretty sharp even after having a few small strokes(TIA).
A few years back, I put together a computer for her and she caught on how to use it quite well. She actually outgrew it and we bought her a newer one a couple years ago. She has become quite the gamer, albeit silly games from Big Fish, but just the same she downloads and installs her own games and has me come to clean up the computer at least once a week.
Though its not a smartphone, she does have a qwerty phone and texts like crazy. Texting has made her shut-in life a little more bearable because she is never more than a few keystrokes away from someone. I have to laugh when I get a text in a meeting and comment "just another text from my 82 year old mother" and everyone glances over at the least tech savy person in the room.
My sister got her a Kindle Fire for Christmas and she is so happy to be able to read again, the text in most books is too small to read. It did take a little adjusting to get used to the touch screen.