The "war on terror" hurt America 10 times more than terrorism ever will
^ This.
Among the people I know in Ireland the initial reaction was very sympathetic. We even had an official day of mourning. However cynicism started to build up when we realized how much the news coverage internationally was emphasising American problems over stuff going on in other places. It felt like the US was getting preferential treatment. And it's true that events occurring in the USA are more likely to have international consequences than those in, say, a third world country, but it felt like we were expected to be more emotionally invested just because it was Americans who were suffering. In particular I think the frequently-repeated "this day will change the world" really bothered some people, in the same way that Americans describing their country as the "leader of the free world" does.
However, that was a relatively minor annoyance. Most people here would still have been sympathetic to the country and to Americans in general. That went down the drains the second the attack on Afghanistan started, and it
really went down the drains when the war in Iraq began. Now the feeling is that America has caused far more suffering and destruction than it had to endure, and that the real tragedy is the civilians killed in Iraq and Afghanistan, not 9/11.
Personally I don't quite go that far. Countries are made up of individuals, and it's not like the individuals killed in 9/11 are responsible for America's foreign policy. But at the same time, it's hard to sympathize with Americans talking about what a tragedy that day was when many of them enthusiastically supported wars that have killed thousands of times more people.