As first time cruisers we deliberately went for short trip from Bergen to Tromso. There was a bit of unnecessary queuing at Bergen to get on, but otherwise eveything went like clockwork.
I can't fault the ship - friendly and helpful staff, clean, comfortable and no pressure to do anything. We're not ones for entertainment, preferring to relax and chat, and this trip was ideal. We loved the fact that it stopped in lots of places, even if not for long enough to get off at all of them, and some were nightime stops so we had to choose between sleep or seeing another place. The constant stops also meant people coming and going, including locals.
We went on a couple of trips off the ship, to the Viking Museum on the Lofoten Islands and dog sledding at Tromso, both of which were great. The former was a real adventure as the wind and driving snow was so bad the coach driver wasn't sure if he could get back to the ship. We even tried reindeer stew which was pretty tasty (sorry Rudolf!) Food on the ship was good, but not huge choice. We love fish, but if you didn't it could be a problem.
One thing I was worried about was sea sickness, but the ship was stable, even during a Force 8 gale. Most of the trip is in sheltered waters, but it does occasionally go out into the wilder seas. We choose one of the bigger, newer ships as we heard the older ones do not cope nearly so well in the storms.
Our hope was to see the northern lights but the weather was not good, and at times there was so much cloud and blizzards we couldn't see anything from the ship - but we can't blame anyone for that.
Would definitely recommend it and are now planning to do the next leg from Tromso to Kirkenes to try to see the lights and also to return during the summer.