My wife and I took a 30th anniversary cruise with Viking, the Vineyards and Vistas cruise. We flew into Frankfurt, Gemany from the USA, then to Nuremberg, where we were met by Viking reps and transported to Bamberg to meet the ship. We felt pretty special the moment we were met by the Viking rep in Nuremberg. It is true that the ship sometimes docks in more industrial parts of towns, rather than the city center, but it's never more than a 20 minute walk to a city or town center.
The cabins and overall accommodations were superb. The cabin attendants really went out of their way to make sure you were comfortable. We had an upper deck cabin, having been upgraded from a second deck cabin just because. We didn't ask for it, but we didn't complain! I've read some reviews complaining about the food service. I don't know how those people are used to eating, but we found the meals onboard to be excellent, plentiful, and well prepared. The tours were generally pretty good, but I can see during the high season that visiting some major attractions such as Heidelberg castle and Cochem castle could be a problem, simply because they're very popular sites with EVERYBODY in the region, hence they can be crowded. But that's to be expected when there are multiple river cruise companies with similar agendas.
Diana the cruise director was outstanding. She's a bundle of energy, and no request was too small for her to act upon. The dining staff really did a great job in my opinion, especially when having to deal with a whole bunch of spoiled, arrogant, whiny Americans. We would have been happy to simply sit in our cabin and watch the world go by, so anything beyond that was just fine. Yes, river water levels were high, and the top observation deck was closed because of that many of the stretches of river, but there was PLENTY of great viewing to be had from lower decks or inside.
Overall we truly enjoyed ourselves and will definitely recommend this cruise to others. The only downer I can really report was that some cruise members were truly old and physically immobile to participate in shore excursions. While that's not their fault, people with disabilities really ought not take river cruises where shore itineraries usually involve a lot of walking. Or, just remain onboard and watch the sights as the boat continues to the next destination while the tours ashore are in progress. The tour guides just cannot accommodate people in wheelchairs, walkers, canes and such, especially when going up hills and climbing steps. If you are unable to get around without any difficulty, then this cruise scenario is NOT for you.