This four night cruise from Punta Arenas, Chile, to Ushuaia, Argentina, on the Stella Australis was a wonderful experience. My husband and I are passionate independent travellers, so we had some trepidation about going on a cruise. However, we loved every aspect of this expedition. We had an AAA cabin, and it was immaculately clean, comfortable, spacious and well designed. There were 140 passengers on board. The ship is very well maintained and it has several lounges for various purposes: briefings, relaxing, attending talks, socialising, etc.
All meals are served in the Darwin Lounge, with buffet breakfasts and lunches, and a three course evening meal with limited choices (usually three mains with one being vegetarian). The food was surprisingly good, and there were always fresh salads available at the lunch buffet for those who prefer a lighter meal. There is an open bar and the waiters and bartenders were always generous in the provision of drinks and snacks. There is also one lounge where self-serve coffee, tea, juice and biscuits or pastries are available from very early to late every day.
As others have mentioned, you're assigned a table for all meals (based on nationality/language) and so you have the same dining companions throughout. This could be a problem if you were incompatible, but our dining companions were lovely and great fun so it worked out well.