Owen,
Are you sure it was a buttkicker and not cheap Aura shaker?
The properly tuned buttkickers will give you a dramatic experience. If there is an explosion in the movie, you feel like your house is coming down. If there is a bullet hitting the wall, you fell that it just went through your body. It is very effective. Again the key is a properly tuned system.
I have also seen people jumping off the chairs beacuse they could not realize what was going on...
