First time river cruising... Decided to try one after 15 or so ocean cruises. It won't be our last.
Viking's staff was top notch throughout the process with the exception of messing up our return flight, but that was minor in comparison to the rest.
We enjoyed having a small group on board (175 or so as compared to thousands on a sea voyage). No kids, no photographers in your face, no art auctions, no broadway-type shows, no talent contests. Just adults, having fun at their own leisure.
Took the optional tour to the Alps. expensive but worth every penny! Standing at base of Mt. Eiger at 7600 feet up was breathtaking!