I have one, (flying up the real stairs at my home is only recommended for ppl with a deathwish) and I defenitely feel it. But then, my stepper doesn't just go up and down, I also make a sideway movement. I've seen those women at the gym on a thing what tony was talking about, barely moving at all, but I guess they just aren't doing it right. When I'm on mine, I move both my upper and lower body and I'm really tired after 20 minutes. Also, it does get your heart rate up, so I think it's good.