I just got back from a January cruise on the Sir Richard With with my partner. Winter is a fantastic time of year if you enjoy the snow because the views are breathtaking and there are no crowds at all! The ship was only at about 1/6 of its capacity and all the sites along the way were clear of crowds. Of course, the Northern lights were very special; saw them 3 time despite cloudy conditions through most of the artic circle. But by far the best thing about the Sir Richard with was 2 hot tubs on the back of the deck, which you could soak in the breathtaking views in comfort and style. Only complaint there is the the ship's railing were are eye level while in the tub, wish they though of that when they installed it!
The ports have a fabulous opportunity to explore numerous towns and cities. The ship had a tourism desk that was a wonderful idea but poorly executed. They only had maps for 2 of the 11 ports we got off the ship, even though each of the town's tourist offices usually produces one. So make sure you research the port cities in advance. The internet on the ship is mind numbingly slow. The excursions sounded fun but we were more than happy to explore the towns on our own.
Instead of booking the full trip, we booked 2 parts: Bergen to Tromsø (4.5 days) then stayed in Tromsø and caught the same ship as it returned south. To me, this was ideal as it provided a much needed break from the ship to go snowshoeing around the beautiful Tromsø area.
Inside cabins are very small but intelligently designed. Thus, very livable. May partner and I put the mattresses of the 2 fold-away beds together on the floor so we could sleep together (the only double beds are in the much more expensive suites!