Ushuaia is the most southern city in the world so its something you kind of have to do. We were there for a few nights and got to see a bit of the town, did a boat ride to the most southern piece of land in argentina and the end of the world train to Tierra del Fuego national park.
The town itself was small and quite touristy (a little overun with american cruise ship tourists) but at the same time it was quite pleasant. The boat ride we did was with Tres Marias on a very small fishing boat. The guide we had was very enthusiastic about everything and told us stories about the natives who used to live on the h-island we visited. They survived in the harsh conditions without any clothing; living off whales and sea lions. We were there with our fleeces and were freezing cold so the survival of the Yamamas people was just amazing. They rubbed whale fat all over themselves to keep them warm, used birds bones as a straws so they were able to get water from the snow and ice and made spears to kill sea lions! These people died out when the white people came around 200 years ago, mainly as their food sources diminished due to poaching etc. There is one remaining native in Puerto Williams but much of their culture is lost as they were raised by white people.
The end of the world train is now a tourist train used to get people the entrance of Tierra del Fuego, however it used to be used as transportation for prisoners in Ushuaia to chop down trees. You can still see the tree trunks on the route we took and it is now known as the tree cemetry. Unfortunately the train journey wasn't that interesting (you'll see evidence of this with Toby falling asleep on the journey!) and we were a little disappointed to pay so much for it and not actually get to see a whole lot. I would definitely recommend walking through the park rather than just getting a return on the train - we didn't do this but I would assume the walk would be much more interesting!
So, after this short time in Ushuaia we wanted to make our way into a warmer climate again. To do this we got a plane to Rio Gallegos and then a 20 hour bus to Puerto Madryn where we spent our last week! You might notice I haven't mentioned Rio Gallegos, and this is for good reason, the place was horrific!