It also depends on their condition. A friend has inoperable cataracts, growing since he was boy, with a later build-up calcium. All he saw most of the time were very blurred shapes, but enough to know whether anyone was moving around him or sitting in from days. However some days this would be accompanied by an influx of light. On others, he would get what he called his 'red mist' - they eyes clouded by redness and he would hardly be able to make anything out at all. In the end, they did operate - not to help him recover his sight but to stabilise the condition so that he could at least plan his daily routine.
'Blind' people rarely see blackness, but have very much degenerated vision.
When it came to using his other senses, my friend always said that it wasn't so much a case as them developing more, but of his becoming more aware of them. He hears much more acutely than I do because he unconsciously works harder at hearing, that being the only way, sometimes, that he can glean information. It's why you should never creep up behind a blind person and say boo.