I would say it is not so much that it is strenuous; it is not a steep incline all the way; the pace is pretty slow and there are lots of places where it is rather easy going. But it can be very slippery in places and requires good balance and sure-footedness.
There is a walkway that goes along side the falls where you can get a good idea of what is involved, as only you really know your limitations. That is what I did--walked along the side first, and decided not to attempt climbing the falls as I'm overweight and my balance is not that good anymore.
But I think I enjoyed it almost as much as if I had climbed it.