For convenience and accessibility, the small ships are great. We have taken several ocean cruises and the size of the ship was a plus. Although our cabin seemed pretty small, we were not in it much. It was very clean and the bed was very comfortable with premium bedding.
The access to ports we would not otherwise have seen was amazing. Heidelberg, Rudesheim and Strasbourg were high spots. Cologne and Koblenz did not have much to offer, we thought, although the cathedrals were beautiful. The included tours are kind of minimal -- walking tours, some guides more interesting than others. Consider doing some tours you pay for. We really enjoyed the Alsace wine tour. The cheese farm in Amsterdam was interesting but I was disappointed it was not a real town, but a museum -village.
Consider traveling with friends!! We did not, and only met a few people we "clicked" with. Evening entertainment is minimal so someone we knew to have a drink with or play cards with would have been nice. The evening entertainment is your meal usually. From 7-9 we were dining, small courses served over a 2 hour period. This got old for me. Every night we were sitting with different people, and some you enjoy more than others. In addition I was tired at night and not always in the mood to banter with strangers. The food was good. Breakfast and lunch buffets were really wonderful. At dinner the entrees were varied and interesting and enjoyable.
The service and crew were great. Free wine and beer at dinner were good. Embarkation and disembarkation were so simple it was hard to believe. Dress was very casual although the weather varied from 40 - 80.
Don't bother to take your computer! I could only get on once in 8 days!
We stayed 2 extra days in Amsterdam, Hotel Eshterea, which is lovely and well located. Get your Anne Frank Tickets online before you leave! We walked right in while the line was very very long! That was plenty of time in AMsterdam, and we may have preferred to tack on more time in Switzerland instead.
This is a very expensive trip, but we saw things we would never see on an ocean cruise and I think its easier than a bus tour, staying in the same room every night. Would river cruise again, on a different route.