Viking seems to have figured out how to have a nice, relaxing time, on board. The ship is beautiful, and the staff truly seems to take pride in it and their work. Everything was clean, food was delicious and service was wonderful.
However, we signed up for this as a Christmas Market cruise and there was very little of that! At each port, we got off the ship and were (literally) marched miles through historical, architectural and/or religious sites, generally with terrific narration. That is the kind of thing I would normally love, but we weren't there for that.
When we were finally shown the markets, we were told we had half an hour or an hour to enjoy the markets before we met the guide. (Except in Cologne, where we were marched through the city and past several markets and told to make sure we were back at the ship an hour and half later as the guide left us there, in the dark to find our way back.)