Scientology is a billion dollar worldwide corporation that disguises itself as a religion. They're completely ruthless, you pay them for every session you have where some jackass hooks you up to a lie detector they call an "e-meter" and makes you regurgitate the worst experiences of your life over and over until you've said it so many times it doesn't bother you to say it anymore, at which point you've made "progress". Everything you tell them is written down/recorded and archived, and if you ever leave the church and speak out against them they publish all of it to their membership to show them how fucked up and untrustworthy you are.
Thats the core of their business, but there is much more. they file lawsuits against anyone who says anything negative about them publicly, especially ex members, and keep piling them on forever until they've driven you to financial ruin to set an example for other would be critics. They have slave labor camps where you can live in a dorm and work for them for free in exchange for dianetics training, and they make it incredibly hard to leave once you join one. One woman was unquestionably murdered (2 indictments) for trying to leave
http://www.lisamcpherson.org/. They have their own psuedo military branch who've pressured judges into illegally obtaining search warrants which they've used to confiscate the posessions of internet critics and the list goes on and on. Several countries refuse to recognize them as a religion, and theyre generally dispised in european countries.
This post is already too long but there is a mile long list of horrible things they do, setup dummy organizations to distribute seemingly innocent pamphlets on manners to kids in elementary schools, which then direct them towards disguised dianetics run foundations, running 5 luxery hotels and other business fronts to suck in celebrities. They invite wealthy guests to their hotels and bug the rooms, to learn more about their personal life so they can attempt to sell them better, as well as listen to how they react to the sales pitch once they've left the room, hire p.i.'s, you name it. Take the techniques of any standard brainwashing cult, fill it full of expert sales people and pump it with an unlimited supply of money and scientology is what you get.
There is a huge movement to warn people about them online, all of the major leaders/organizers such as those from the alt.religion.scientology usenet group have been sued by them nonstop for upwards of 10 years. They strongly discourage and in some cases forbid members from using the internet or watching any of the dozens of exposes that have been on various news shows and magazines. Generally any news outlet that does a story on them is sued the day after it airs.