Having been on mega cruise liners and being part of the crowd, my wife and I prefer the smaller river boats. The Helvetia was exactly what we like, and was the second "small boat" cruise we have been on. The 8 day Rhine Getaway was a perfect way to see this part of Europe, with excellent on board service, great food, wines and shore excursions. We took many of the packaged shore trips, but did venture twice on our own into the towns at which we were docked. Most ports had the docking sited right off parks along the river, and it was a simple stroll into town. As the boat had less than 200 passengers you did not feel like the boat's passengers "took over the town", as happens when a large cruise liner docks. One of the less publicized sights within walking distance of the boat when docked at Speyer is the Museum of Technology. It is an eclectic collection of aircraft, boats, vehicles and other devices. Many are from WW II. They even have s space shuttle, a Russian craft.
Though, due to its size, the boat had little on-board fitness facilities, the daily shore excursions offered multiple opportunities for walking to whatever degree one desired. In most ports Viking has contracted with small teams of local guides all who offered great perspectives on the local sights and cultures.
We only found two minor issues with the trip. First was finding the Helvetia in Amsterdam. Our embarkation instructions indicated that it would be docked at one of three locations. Naturally it was at the third one we tried. Fortunately we had spent time in the Netherlands with friends, and they drove us to the docks. Had we taken a cab, this would have been a major complaint. I would think Viking could have emailed all passengers a day or so before telling which dock they would be at. The other minor issue is internet service on the boat. Yes, you could get good wireless connection to the boats server, but rarely did the server have access to the outside world. Basically internet worked only when we were docked at major city ports.
However, we did not take a river cruise to stay on the internet. This trip was one of the two best cruises we have taken.