I've seen that site before. There is plenty of info out there praising landmark.
I think the key might be for a person to read both sides (as I have- you wouldn't believe how much information I've read and considered in the past several months) and come to a conclusion on their own.
In reading the first two letters from professionals in the mental health field, both of them describe their definition of "cult" and neither definition is correct or complete in my opinion. They are much too easily dismissive of the issues that raise alarm and because they are directly associated with Landmark, cannot possibly provide a non-biased viewpoint. But then perhaps you aren't looking for that. There are statements made by those "professionals" that I believe to completely false.
They offer no explanation for the many people who have sought therapy after a forum. For the many problems that people have trying to take the "technology" and apply it in the real world. They offer no help to someone who has watched a loved one change in an unhealthy way, except to tell them to do the Forum themselves so they can "understand".
Find someone who's lost a husband, wife, or daughter to Landmark and try to convince them it's not a cult. Explain to them why their loved one has cut them off simply because they won't do the Forum for them. Tell them why their loved one has spent money they don't have for courses that don't seem to give them any sort of benefit, and in the meantime have let the important things in their lives slide because Landmark Education takes up all their time. Look these people in the eye and tell them their loved one is really happy and well adjusted and living a life of possiblity when they are about to lose their house and are getting divorced.
Want to look at another point of view? Read this site and tell me what about it isn't correct: