We mainly went to see the Northern Lights. We saw them on a number of occasions, which was great, but they were slightly underwhelming. They were mainly white light / only showing green on very slow exposure photographs.
The ship was comfortable, the crew and food were excellent. Drinks were expensive. £15 for a glass of wine, £10 for less than a pint of beer.
The excursion in Tromsø was amazing, packed a lot in and was great value for money, but on a lovely lakeside walk in Hammerfest we were charged 379 kronor / £33 each for a tiny cardboard cup of tea and a small piece of dried reindeer meat.