After 3 days in Prague we were supposed to board the ship at Nuremberg for a cruise to Budapest. However, at the last minute we were advised that the river was too low and we would have to be transported by bus to Passau. As a result we missed out on two of the seven days cruising we had looked forward to. We were later told by a member of the Avalon staff that this situation is not unusual as the Main River is often low in June.
The boat was very nice, the food was excellent, the service provided by boat staff was excellent. However, we were very disappointed by the loss of those two days cruising. In our opinion we had paid top dollar but for two days we were provided with a mediocre product. We did not get what we had paid for. Avalon staff told us that they do not compensate passengers for this loss. Our advice - research the river you will be travelling on with respect to how often it is not navigable during a certain month of the summer.
One last note. Do not take a river cruise if you like to eat by yourselves. There are no tables for two. You will have no choice but to eat with others, some of whom are delightful, others less so.