Just completed the Viking River Cruise "Paris to Prague" which includes a river cruise from Trier, Germany to Bamberg, Germany. The Paris to Trier part and the Bamberg to Prague part of the trip are by bus. Trier to Bamberg is along portions of the Moselle, Rhine, and Main rivers. My wife and I booked what we thought would be the vacation of a lifetime. On the Viking ship Odin, we booked a two room suite with small balcony looking forward to amazing views and luxury service. The entire trip was good - but not great.
The pros: Nice ship, wonderful service by the Viking employees, good food, Paris and Prague were amazing. Loved the scenery along the Moselle and Rhine. The optional excursion to the charming town of "Rothenburg ob de Tauber" was the best of the cities/towns on the cruise portion.
The cons: Way too much use of busses along the river cruise portion, the top "sundeck" was closed for the entire back half of the trip because of low bridges (that's the place you want to be with a glass of wine and taking in the scenery), some of the docking areas were is industrial areas far from the cities/towns centers (ergo the overuse of busses).
Very nice two-room suite with a small balcony. The wi-fi on the ship was horrendous to the point of being worthless (everyone complained about it) and the television selection and service was bad.