Has anyone been on one of these? Any comments,evaluations, suggestion of companies etc. appreciated.

Check the Washington Post Travel section archives -- a couple of months ago there was a very detailed review. Plus their articles always include "contact" information. www.washingtonpost.com

I went on one of the KD Rhine-Mosel cruises years ago and did not care for it. Loved the towns, the castles, and the scenery but really did not find the ship, the meals, or the service to be good value for the money spent. Recommend doing it yourself by train or train-boat instead and staying in B&Bs in the towns along the way.

You do not say if you are talking about a 1 to 2 hour cruise or several days cruise. We were just in Budapest and took a 1 hour night time danube cruise which was wonderful. Most of the major monuments and sights are within view of the river and are lit at night. They have ear phones for each language providing historical comments and also have monitors to augment the discussion. The Rhine also has cruises but are not as informational. This allows you to stay where you choose and eat what you want, but requires more planning for transportation.

I have never heard much good about the ships themselves for overnight cruises on the Rhine. My suggestion. Stay in the wonderful small towns along the Rhine and travel by boat from one to another. And don;t miss the Mosel also and a trip to Cochem. We were on EurailPass and travel on the boats was included. Spent four or five days in the area actually using the boats as transport from town to town -- Rudesheim, Koblenz, Cochem, and then Cologne. That was a wonderful way to see it.