There is a sight-seeing level on the lower floor. On the upper floor is a revolving restaurant, which gives a birds-eye view of the fjord and city below. A full turn takes one hour and so by the end of your meal you will have travelled at least one round.
The best time to visit the tower is for sunset so you can watch the panoramic view change colour. If you have been touring the city all day, you will be able to track your journey through the cityscape and pick out the landmarks you visited.