Is Abu Ghraib an isolated incident? Of course it is. If you know anyone whose been in the military, or went to high school even, you know that despite the rules and morals we were given from a young age, there will always be people who must act like animals (especially in high school).
But most, and I emphasize most, military folks are decent and polite Americans who know their place in the world and are secure with that fact. Take this discussion between two Iraqis about conditions as the prison in question (Hat Tip: Winds of War). Sounds like they are pretty sure.