Chose this trip with the help of a Travel Agent who pitched us at the right level of formality.
The age range of passengers was predominantly 50+ although there were younger people, children and babies but everyone we met was friendly and willing to talk and share experiences (not always about cruising but about lives in different countries). Majority of people were from America.
The Norwegian Star seemed a big ship to us which meant we did not feel confined at any point and provided variety for eating and entertainment. Having not cruised before could not say what size ship we preferred but do not think anything much smaller would suit us although I accept this is personal preference. There was one formal night known as dress up or not and there were those that did the full whack with tuxedoes and long dresses and those that didn't. It wasn't a problem either way.