In Nov 2011 we booked a river cruise through Viking for a 15 day cruise sailing the River Rhine from Antwerp to Basel, Switzerland. Food was average, crew was great, room great, and ports of call guided tours were perfect.
The problem came half way through the cruise and we were off loaded onto buses to finish our 'cruise' staying in hotels, on and off buses, and dealing with packing and unpacking. These are the reasons we booked the river cruise was to not have to live in hotels and buses....we've already done that several times and now we are ready for the lazy days of a river cruise.
Water levels being low was the reason given which is true, the problem was Viking knew this well in advance, knew the cruise couldn't be completed without the bus tour and never once offered us the opportunity to postpone our trip for a later date or make any other arrangements. They didn't say anything until the night before we were put on buses. Other reviews indicate at least in the past 12 months, this has been how they operate and is no way to get repeat business.
For our 'trouble' they offered a 30% off what we paid for this trip to be used as a credit for another cruise within 12 months. That doesn't come close to being the right thing for them to do under the circumstances. A partial refund for this part of the trip is the right thing to do.
Do your homework before booking a cruise with Viking as you can't count on them being honest with you about your trip.