The Mormon church is two centuries old; most "cults" do not last that long. Remember, the US is a very new country, so the Mormon church has been around almost as long as the US has existed. However, what is a cult and what is an established religion is largely a matter of opinion.

One thing that makes Mormons controversial is that they have practiced polygamy (men having more than one wife) for most of their history, and this is both illegal and in theory immoral in the US. Another thing that makes Mormons controversial is that they claim their church was established by a propet, Joseph Smith, who was chosen by God to correct errors in what other Christian churches were teaching. This kind of claim is always unwelcome to members of an established religion, but it happens over and over again, and not only in Christianity.

There is another religion, Christian Science, which has a status similar to that of the Mormons, but they are not as controversial, and for different reasons. Christian Science is about 130 years old, so it has also stood the test of time, but it, too, is regarded as strange by most mainstream Christians.

I am not a Christian (or a member of any organized religion) at all, so I am viewing this question from the outside. A mainstream Christian would be more likely to tell you that both of these churches are "cults."

Here's a video that describes actual Mormon beliefs:

I wouldn't say they're bad guys. I have no interest in Mormonism, and they were certainly on 'mission' to convert people when they met you--and may not actually be interested in people who don't want to convert to their beliefs--but it doesn't mean they're bad people.
I grew up near Mormon neighbors, though, and they tended to dislike anyone who they failed to convert, so we didn't get along...@0@

I don't know what the source of that video laowai1965 posted is, but it was clearly made by someone hostile to the Mormons, and I believe much of it is exaggerated and distorted. If you want to find out what Mormons say they believe, I think it would be a much better idea to consult materials written by Mormons themselves.

I don't have strong feelings one way or the other about Mormons myself-- I think that as in any other group of people, I would like and respect some of them, and not others-- but I think it is very unfair to represent the beliefs of any group the way that video went about doing it.

@Tony

The video treated Mormon theology with humor, but it was a fairly accurate description of traditional Mormon theology. I would be interested to hear what *specific* parts of the video were "exaggerated and distorted" as you claim.

To be fair though, the video presents what would now be called Mormon "fundamentalism." In the 20th century, the mainstream Mormon Church abandoned a lot of this doctrine (including polygamy). However, there are Mormon fundamentalists who still cling to all of these doctrines. Also, to be fair again, most mainstream religions (which, as Tony pointed out, differ from "cults" only by their longevity) contain beliefs (eg virgin births) which are just as irrational as anything in Mormon theology.

If you want to know about Mormonism, I am a member of the church and I can answer your questions. We are called The Church of Jesus Christ of Latter Day Saints, but most people know us as 'Mormons'. The two Americans you met were some of our missionaries, who take two years to go preach the gospel. I'm about to go on a mission as well, so I would love to answer your questions.
Hope that helps!