I tried this today, with some concerns, since I didn't give myself the time to do all the stuff to prepare, so I was focused on what could wrong.
Worrying about showering(which I didn't have time for) and shaving(which I didn't), and getting nails clipped(I can't reach), and shoes that were too tight(have to return AGAIN, which will be hopefully accepted for an exchange), and having thick socks(with a hole which was finally mended) made me irritated. I waited and saw no-one at the class, because the instructor nearly left, and apparently locked the door.
Moving slowly, helped me, and I became aware of my pains throughout my body, so there was some guidance about find the posture of comfort. My fear is of being drawn into a philosophy contrary to my religious beliefs, but it should be okay, and I felt okay.
Everything doesn't have to be an orgiastic experience, I suppose.
I'd really rather be kung-fu fighting, but I'd get hurt in the process, so I'll see how I feel later.
I'm impressed that the instructor has a martial arts background, so maybe some day, I can have "hands of lightning".