Pit bulls are, genrally, highly recommended as family pets because they are extremely gentle. It takes a lot of work to turn a pit from that gentle nature into a violent dog.
I've known two people who raised their pits to be gentle dogs whose pits bit a person. In each case it involved the pit in a fight with another dog and someone trying to break up the fight.
Not saying they're bad - I just think some folks don't appreciate
a) dogs need to be tought to socialize well not only with people - but also other dogs
b) you never try to physically break up a fight between dangerous dogs like that. In most cases the fight will settle itself - if they dogs are normal and aren't trained to be killers, one will eventually realize he's lost and submit to the other - and - the best way to break up a dog fight is to turn a water hose on them - or failing that - throw water at them.