The main problem was that there was insufficient water in the Elbe to cruise. Viking knew this well in advance and should have given us the opportunity to cancel and receive a refund.
They also changed hotels after they confirmed our booking. Instead of the Marriott in downtown Prague, it was changed to the Corinthia in the suburbs. Not a good hotel and had to get the metro to go into Prague.
Had to bus from Czech Republic to Germany to board the boat due to low water levels. Spent 4 hours total cruising the river. The rest of the time we were bussed everywhere.