There's no body banging. They tend to bang your head more than most B&M's do though.
You kind of sit on a bicycle seat, but more or less you're standing up like when you sit on a bike and touch your feet to the ground. There's an Over The Shoulder restrain just like on a B&M looper. They adjust the height of the seat and shoulder restraint to each rider's height before locking it. Some males complain of "groinal discomfort", but I've never had that problem as I always make sure the bicycle seat is low enough when they lock the position so my weight isn't on the seat, but rather on my legs/feet and that is how you are supposed to ride. The seat is only there to give your legs some added stability. It is not meant to be sat on.