What happens when someone wakes up from being in a coma?

It's good. First off, if one "wakes" up from coma, it is a good sign. It's hard to tell what one feels when it happens but i would say it depends on the cause of the coma. Some may feel generally weak, but have all their senses back to normal, while others may have some physical and mental deficits that may either stay for a while or become permanent.