I had taken a river cruise on Viking in the past and felt very comfortable with them. I've found their ships very clean and staff very accommodating. Food was excellent with many choices. If you needed it fixed a special way they went out of their way to make it happen.
Staff was always pleasant, friendly, courteous and professional.
The tours well very informative and there were a number of choices. Activities were rated for activity level and very descriptive making it easy to pick ones you are comfortable with plus one can can do things on their own or stay on the ship.
Always clean and well stock. The steward was most courteous, friendly and professional.