No experience, but I would bet that vice president guy who does the TV ads spends a lot more than 20 minutes a day on one!
Also, I would think of it as a lot like weight lifting, so check with your cardio as to how much weight/resistance is acceptable or appropriate, given whatever limitations you may have.
Those black "resistance rods" are some type of plastic, so at least it wouldn't be too heavy to move the machine around.