Low water on the Danube reduced the 10-day cruise to a week, with the remainder of the time in hotels in Budapest and Bucharest. "Included excursions" were often long bus rides from the Danube. Transfer from Budapest to Mohac, and from Nikopol to Bucharest were long, exhausting, and the major consequence of low water.
Viking "system" greets passengers from airport arrival to departure. This aspect of the journey can be very stressful, but the Viking way makes it easy. The hotels were fine (Hilton West End in Budapest and Sheraton in Bucharest), if not necessarily located in prime tourist neighborhoods.
Dining was an issue for us due to diet limitations (we can't eat lactose, and don't eat pork or shellfish); the maitre de (Gabor) did an excellent job assisting us. Only issue is the inflexibility of the dinner: 7:00 PM. There is no alternative.
Tiny! No room for even a chair. Major positive is closeness to dining room and stairs.