We had a wonderful tour with one of Edgardo Calaio's group of tour guides December 28, 2012 in Ushuaia Argentina.
We were a group of 14 from the Star Princess. Our guide had a well prepared speech. He passed around items/pictures during the bus ride. The small bus was very comfortable with an aisle down the middle of the bus for easy ingress and egress. Any walking we did I would rate as easy. The National Park is a must to see. Even though we were there on a rainy day it is a beautiful park.
I would definitely recommend Edgar guides. You can contact him via his email edgardocalaio@gmail.co