We were on an Amsterdam to Budapest cruise. Our first river and Viking cruise.
Viking did not notify anyone until the night before the cruise that there was a problem with low water level in the Danube, preventing our ship from reaching Amsterdam. Fine; we boarded another ship that was a carbon copy (the Wili) and took us as far as Nuremberg where we were then bused quite a distance to the Mimir on the Danube. This required packing up the night before. Then we were unable to get all the way to Budapest and had to be bused into that port on th last day of the cruise. Rather than be bused back to where the ship had docked, we just stayed on in a hotel in Budapest. We were also given a group lunch on a barge in Budapest that was billed as typical Hungarian fare that was a piece of grilled chicken and a dollop of rice. Cafeteria food.
When docked at several places, we would have a wonderful view across the river only to have another Viking ship dock parallel to us, blocking our view with a passenger cabin about 2 feet away from ours. So we had to close the curtains and turn on the lights during the day. Felt quite confining, and annoying. I assume Viking "double docks" like this to save port fees, though I really am not sure.