We had previously cruised with Viking in April 2015 - that being the Tulips and Windmills cruise. The entire experience was so wonderful and such a joy that we decided on a Viking Christmas cruise. We love the ambiance of the River craft and the personalized service that all guests receive (we did and assume all others did as well). The ships themselves are kept very neat and clean and the cabins also. While the cabins are a bit small, I can see that the public rooms benefit from the additional space. Nobody spends much time in their cabins other than to sleep and shower.
The dining room offers a great variety of dishes and are beautifully presented by an always friendly wait staff. Again, the personalized service adds to the experience of everyone being made to feel special.
The on board activities were a fun way to wind down after a day on shore seeing the wonderful sights and having a great experience. The piano in the lounge is always a nice touch as it adds to everyone's relaxation. The games (per se) in the lounge are fun and a good way to get conversations started.