Viking is ok as long as the rivers are navigable. Day 1 the river was too high for the boat to meet us at our embarkation city. Instead of putting us up in a hotel and allowing us to tour the embarkation city we had to wait in a conference room in a hotel for 4 hours after flying 11 hours. Then we were put on a bus for a 3 hour trip to the next port where the boat was docked. Day 2 we were told the river was too low to leave the city. We paid for a river tour of 5 cities and only saw 3. Once we got back on schedule the trip was ok. After missing 40% of our trip VIking offered a $500 refund on a fare that was over $8000.
Like other reviews I have read on this website, if there are problems with the water levels on the river then Viking does an absolutely horrible job of accommodating it's passengers. After being in business for so many years you would think that they would have developed a better way of dealing with these situations other than telling the passenger "we are sorry".
Viking customer service could not care less.