This was my 3rd Viking River cruise and I have a few more I intend to enjoy as time permits. Viking takes care of you from the minute you step onto the airplane at your home airport (if you use Viking Air) through to when you step on the airplane at your return airport.
In between, you are educated daily about tomorrow's adventures (tours) which are included int he price including skilled professional bus drivers and local tour guides, often educated and interesting locals rather than tired droning traditional guides.
The food and the service onboard is excellent and often the company is as well, because you will be traveling with like minded guests interested in more than palm trees (not that there is anything wrong with palm trees!)
I have invited 3 travel companions to join me on Viking Cruises and all are interested in repeating the experience. In a couple months I will be enjoying my first Viking Ocean cruise, if they do rivers this well, the ocean is going to be grand.
Being perfectly honest, the cabins on the longboats are small, very small. Buy the largest you can afford. I highly recommend a balcony. I had a French Balcony the first trip and know better now. Fortunately, you are very busy and not on the ship much and the public areas are comfortable and inviting to spend time in.