Traveled with my sister and her husband, Oct 5 - 12, Basel - Amsterdam. The ship was clean, food was fair to good, wine selections poor and included internet virtually unusable due to extremely low speeds (10+ minutes to load a page!).
The included tours, were, for the most part, a waste of time. The Black Forest tour was a 1.5 hour bus ride to reach a small shopping center, missing Freiburg and other interesting sites. The Cologne city walking tour was a brief tour of the Cathedra, interesting, but brief and far short of seeing the city.
The optional wine tasting tours were also disappointing, Fairly long bus rides to visit a single winery, tasting 3 varieties, and then having ample time to buy their offered products. Once again, a tour that I paid for, only to be shepherded to another shopping venue.
The only tours I can recommend is the village of Colmar, the Ehrenbreitstein Fortress and the Bruhl Palace.
The last full day of the cruise was spent at the "Kinderdijk windmills", while somewhat interesting, certainly not worth an entire day of the cruise. This day was wasted, as the cruise could have visited Rotterdam or the Hague, rather than sitting in the middle of nowhere for 12 hours.
I've spent the same amount of money/day on Crystal and AMA with much better results. Don't waste your time on Viking River cruises.
Clean and well maintained