Our neighbor has two dogs - one a male Black Lab and the other a female Bull Terrier mix - the mix looks like Black Lab to me. While they both could use a little obedience training (the female is also barely a year old), they are both really sweet dogs. They have a young boy, almost 3, and twins on the way.
The two dogs will run around their yard - almost an acre - all day chasing each other, wrestling, playing tag, tug of war, etc. Sometimes you'd think they are going to kill each other by the way it sounds. She (Eve) will come up and chomp on his (Jack) tail and then run off and so it goes. It's hysterical to watch, especially when they are both busy digging up a shrub.....(hence the obedience part). Glad they are not my dogs....but then our two English Cockers aren't exactly perfect either...
But, getting to the point - our neighbor was worried about having a Bull Terrier around kids, but aside from beating up on her "big brother", she's a big marshmallow and loves people, strangers, etc. I've seen absolutely no aggressive tendencies whatsoever. I think the mix of Black Lab makes the difference.
But, I firmly believe that aside from simply poor breeding, there are no "bad dogs", only "bad owners". German Shepherds had a bad wrap from poor breeding as well as American Cockers. I don't think there is anything "wrong" with Bull Terriers except being bred/raised for aggressive behavior. I'm not a fan of terriers in general, or Schnauzers, but have known some really good examples (and poor) of both.