I was going to say the same thing about Pittbulls, Rotties and other powerful breeds. They are not dogs for a novice dog owner. I think they are one of the most loyal breeds that you can find but they do need a lot of discipline and a firm hand (by that I don't mean beat them or punish them excessively), and mostly consistency.
Most people don't know much about dog psychology and problems arise when people think dogs have human emotions and treat them accordingly. With many dogs you can get away with it without too many problems, not so with most pitbulls and rotties. With pitbulls you have to establish your role as the packleader and it's not always easy, pitbull or not. Once they think they are the boss of the house you have a ticking time bomb on your hand.
Pitbulls are not so much people aggressive as they are other animal aggressive. Most pitbulls even if socialized have a very low tolerance for other dogs. As someone who has witnessed two pitbull attacks on one of my dogs, I can tell you it is the most guttwrenching thing I have ever seen and those two pits were owned by people who had no idea how to properly train and control their dogs. Not because they were mean people but just because they didn't know, they thought their dog wanted to "play".
My dog survived the attacks because I was prepared and maced the pitbulls. But it has turned my formerly gentle, social and playful puppy into a nervous wreck who goes ballistic every time he sees another dog. Do I blame the pitbulls? No! I blame their owners!
I think people have best of intentions and they mean no harm. I just went to a pet supply store on Friday and there was a pitbull puppy and a Labrador, so they were sniffing and doing their thing when all of a sudden the pitbull jumped on the Lab and nipped his ear. Instead of correcting the pit, both dog owners were just standing there and ooohing and aaaahing "awwwww, look, how cute" "They are playing". Ummmh, no, it's not cute! It's leading the dog on the wrong path. Eventually the Lab got fed up of the pitbull puppy's behavior and rightfully growled at him, he was the one who got yelled at by both, his owner and the other dog's owner.
I have had dogs for the past 12 years, at one point I had 11 dogs in my house, I train dogs, and I still don't think I have it in me to properly handle a Pitbull, Rottie, Doberman, etc.
I am sorry for preaching and if I offendended any Pitbull lovers but this is one of my pet peeves! Pitbulls are great dogs but they are not for everyone.
I just wanted to throw in my 2 cents, as well. I have never had a better running partner than my Doberman/pit bull mix. We have three kids that she is absolutely fabulous with (she even lets our daughter dress her up, the poor thing! 
