My sister had an ex who owned two pit bulls. One of them was white and deaf, and was super sweet and cuddly. The other one was a pit bull/lab and wasn't so sweet. He had to disown her because she was so hyper. I think she attacked someone's dog.
The thing that people don't understand is that every dog has a breed temperament. Pit bulls were bred to fight, but not against people. They're naturally aggressive, but not in the way like it sounds. Every dog has a different personality.
I would definitely own one if I could. There's a ton of pits stuck in the shelter, but a lot of them do come from difficult backgrounds. One time my mom met a pit bull in one of the local shelters and it was being all happy and friendly until her boyfriend came close. Any type of dog can become human aggressive if they're treated badly.
I'm glad people in this thread aren't throwing around the "nanny dog" thing.