Aww - it was the most amazing holiday - I loved it!
The ship was great (we were on the Balmoral which is the oldest and smallest - it's a bit faded grandeur, but has a really nice feel. Our cabin was on deck 5 in the middle - very happy with this positioning as we high up enough to have lovely views and in the middle = less rocking!
The North Sea crossing was bumpy both ways, so I was glad I'd taken travel sickness stuff, but once we got over the sea it was amazingly smooth!
We only did a couple of organised trips - an arctic train trip which was incredible and a coach tour of Alesund on the final day as we knew we'd be knackered by then! On the other days we stopped we did our own thing - Tromso was very easy to do independently and we managed to do the cable car, cathedral and look around the town on our own, taking a couple of ubers!
The passengers were probably in the 50's - 70's age range - I'm mid-50's and felt very at home..! There were a few people a bit younger, but yes, it was mainly 50+ and pretty sedate 😀
Clothes - I'd taken a couple of posh sparkly things for formal nights - literally the first time I've ever dressed up like that... There were 2 x formal nights during the 10 night cruise but it's not compulsory to wear sequins - was just nice to do - but anything posher than jeans would be fine. Mostly people did make an effort at evening meals and dress down during the day 🙂
really hope you enjoy it if you book it - I'd definitely do it again!