Heads of state, prime ministers and foreign ministers later this month will descend on the United Nations for the annual opening of the General Assembly.

It is a time of change and ambitious action for an organization often criticized around the world.  The U.N. is led by a new secretary-general and is preparing to launch a large peacekeeping mission to the Sudan's troubled Darfur region.

Reporter Nathan King followed along on a tour of the U.N. to gauge visitors' attitudes.

The U.N. is about to play host to presidents and prime ministers from the four corners of the globe.  Every year, hundreds of thousands of tourists also visit the New York headquarters.  Their views are not always friendly.

"They get paid too much."

"The United Nations is in the hands of the United States and the rest just follow along."

"We want to join."

Whether it is residents of Taiwan who want recognition here or  Europeans who say the organization is bloated, tourists often express such judgments.

Tour guide Anima Dua Agyman from Ghana  hears it all. "It is not just Americans. There are people who feel like that the UN is just a waste of time, -- [that] it is just bureaucrats who are just taking time -- who feel like they are just wasting money.  And you do not just get Americans.  You get that from Europeans.  You get that from people all over. The U.N. is not a world government."

In a variety of different languages -- six days a week -- U.N. tour guides respond to people who express the belief the organization can act unilaterally.

"But more and more I am realizing that the U.N. is made up of my country, your country, and everyone else's country. The work of the U.N. comes through the work of the people -- in other words -- the work of all these different countries," says Agyeman.

"Does anyone know who the current Secretary General of the United Nations is?" she asks a group.

On the tour, the guides explain the workings of the Security Council, the General Assembly and peacekeeping.  They also point out U.N. pursuits that do not often draw headlines, such as efforts to reduce poverty.  That surprised some of the group. "They spend 80 percent of their funding on social issues. At first, I thought that they said 18 percent.  Then she said 80 percent.  So, I mean, that is pretty great they are fighting for so many issues."

World leaders who arrive here for the General Assembly later this month -- much like international tourists -- often express widely varying opinions about the U.N.'s mission and effectiveness.