N.P.
Lisa is correct about the principles of Landmark Education coming from Est (which was heavily criticized for being cult-like). That said, I have MANY friends who have been through a variety of programs offered by Landmark and I have watched them grow into incredible people...Landmark gives them some very valuable distinctions for how to live their life in a more powerful manner. I have never been through a Landmark program myself; I've been to a few "information meetings". The biggest problems I see with Landmark are not so much with the program itself, but rather with how dependent some of the participants become on the program. The ideas and principles they learn at Landmark existed long before the program and will be around a long time afterwards...but I've had people tell me that I wouldn't be able to understand a particular distinction because I haven't been through a Landmark program. I've also seen people become "program junkies"....as though the only way they can continue to live powerfully is to attend every single program that Landmark offers.
My personal opinion is that if you're actively looking for opportunities to learn and grow, and you can comfortably afford to attend the seminar, then go with an open and thoughtful mind. If money is tight (which I know it is for a lot of families), put the opportunity on the backburner for now and revisit it later. There are enough resources in the self-help section of Barnes and Noble that have similar underlying principles.