Right from the beginning my grandsons, ages 7&9 loved it. The upper choice was a bit too much for my 7 year old but he had a blast on the lower deck, and was even running parts of the course. My 9 year old did both slowly at first and then was running and smiling and totally enjoying it.
They both said they wanted it to do it again, but wanted us to buy the package with more zip lines.