First of all, I would only recommend this stepper to people with good knees.
The stepper came right on time. I ordered it because I don't have a lot of time to work out. It is very easy to assemble the few extra parts (workout handles). It also has fairly large platforms for your feet. It's easy to use and not hard to balance when using.
I'm 54 years old and I have torn a meniscus in one knee and arthritis in both. I've always been athletic until I tore my knee cartilage. I didn't think this device would be a problem if I was careful. I only used it for about 5 minutes the first day. I did work up a sweat, but the next day, my "bad" knee was painful and weak. It took a few days for the pain to go away. Now I do use it, but for only a minute or two, a couple of times a day maybe. I've only had it a couple of weeks, so I am hoping that I will gain knee strength enough to use it as intended...about 10-15 minutes (as per manual). If that doesn't happen, I can forget an aerobic workout of any kind on this stepper.