We went at the end of November, and it was very cold! This was a really nice trip with lovely views and a good way to get on the water while staying in Oslo. However, after the first hour it became a bit gruelling due to the cold, so perhaps a shorter trip in the winter, or go in the summer. There were lovely warming drinks available at the bar but they were quite pricy.
The views were nice, the commentary interesting and there was a useful stop at the museums (though you have to go on the morning boat if you want to catch the boat back), but overall the trip was pretty average. The seating area was overcrowded, with people having to stand for the entirety of the 2 hours if they got on too late, and if you sat on the right, you missed a lot of the views that the commentary was telling you about, which were on the left and covered by two rows of tables.
Overall the layout, the lack of cover in the cold weather and the overcrowding took the trip from great to just nice, but it was a fun experience and I'm glad we went.