We wanted to see Prague and Berlin thus chose the Elegant Elbe river cruise. We purchased the 2 day Berlin extension and would go back to Berlin.
The cruise itinerary exceeded expectations as it was all in former Eastern bloc areas thus very historic (in my lifetime). Viking did a great job with programs / speakers that could provide first hand experience with the Velvet Revolution. Cruise offered a combination of delightful rural cruising, small historic villages, larger cities, Lutherland, Saxony Switzerland, and large cities Prague and Berlin. The Elbe is a recreational river thus only a couple barges; mostly pleasure crafts. Food was outstanding combination of local favorites and classic entrees at all meals. Pre-cruise I found the itinerary provided lacking adequate detail to be useful - both printed materials and Viking website. I get that cruising can be unpredictable but at least provide a general idea of target times, like latest time likely to arrive at hotel from airport, for example.
Schumann is a smaller ship which provided plenty of charm. Service, food, scenery was all was excellent. Cabins have twin beds - OK with us. Air condition in cabin didn't seem to remove humidity as expected.