OK, against my better judgement I'll respond to this.
First of all I think you should know that if you ask a question like this you are asking for individual opinions. I will not speak for anoyone else but me. It might be good to remember that you asked their opinion of the U.S. (I'm going to take the liberty to assume you're not asking my opinion on Brazil, Mexico, Canada, the U.S., Argentina,.... combined). It's good to keep that in the back of your mind, since most people have opinions about just about everything and everybody, even themselves and their own country.
As for the Americans (of the U.S.) who barge in here and say they don't care what all these idiots think of them.... then you wouldn't have come in here.
Now, as to my opinion on the United States of America as a country and its inhabitants:
Over the years I've gotten to know quite a number of Americans on a personal level and professionally. I've been to the States on a couple of occoasions (together with trips to Australia and Canada and a good chunk of Europe) and for the most part I observed that they were just regular people, but with a slightly different culture, of course. The most notable differences I saw were that they were very open and friendly, but bordering on too familiar looking from my own cultural background. This isn't anything bad or anything, but it is perceived as fake in my culture. Again, percerption, since I wouldn't want to step on any toes of Americans who "don't give a f*** about what everyone else thinks". I also noted the Biggest, Fastest, Highest, Loudest cliché to have some basis of truth. Also the ability to commercialise just about anything. These are some of the common traits/differences that struck me when I was there, but don't really worry me.
There are some things I do worry about though. Again, I have such worries about other nations, inculding my own, on other matters as well. But you asked my opion on the situation in the U.S., so here goes:
The education and media seem to focus an awful lot on the States itself. Of course, there are exceptions to this, but in general this is the case (just mentioning my own observations). This leads to a tendency to reduce other cultures or countries to stereotypes (yes, I know the irony of mentioning that here). This is, of course, quite normal behaviour, which I would gladly put in the list above this one, were it not for the fact that the U.S. has a tendency to project its power. I did also see a difference in how different people handle stereotypes and people in the States have a tendency to take them a bit more serious than people from other parts of the world I've encountered.
Years ago I've also encountered quite a lot of political, cultural and historical naivety (defenitly not all of the people I knew, but still a majority) which was probably caused by Hollywood and the media. Expecting to be hailed as libirators in Iraq, thinking America (or any country, for that matter) is the best country in the world and everyone wants to be like them. The fact that a lot of them actually thought that Al-Qaeda did what they did because "they hate our freedom"
The negative reaction of a lot of people towards universal health care shows me a real difference in culture and way of thinking, but matters such as Creationism being taught in school as biology in some States personally make me cringe and I hope that eventually it'll blow over.
The fact that a lot of the idiots in the States are quite vocal doesn't help the general international perspective. Fox News isn't winning you guys any favors. Neither is the WBC. Fortunatly there are people like Jon Stewart (he should get a medal from every embassy America has

).
The state of the world has made it so that the U.S. has become what you could call the world police and just like all cops they're not liked when they show up uninvited and "they're never there when you need them". Comes with the territory. This is a very simplified summation of a more in depth view, but your question was how you were perceived. I know you can't make an omelet without breaking a few eggs, but that doesn't mean that you won't be blamed for breaking them.
In short: the U.S. is just another country, not the best, not the worst. I perceive you as being slightly different from me because, frankly, you are. This isn't good, this isn't bad, this is just a fact. Do with it what you want, it won't change much.