Yes, it's a wonderful trip! I enjoyed the Christmas Markets in Alsace over most of the German ones surprisingly, the best Glühwein was in Strasbourg, best and only Glühbier was in Koblenz (!), pre-trip in Brussels/Bruges was wonderful with Thijmen and the post trip in Basel with Johannes also a great time. Thijmen was our PD the whole cruise, too, and he was excellent. Our Lucerne day didn't include as much as yours, because Johannes had made reservations for us at the Fondue hut in the Christmas market.
I agree about the wine! I was on the River Concerto Rhine cruise, too, and the wine was not great. We called it German box wine, but that didn't stop most of us from drinking it though. I should have been going for beer instead, as it was much nicer as I discovered near the end of the cruise. Everything else with the meal service was wonderful, and the quality of the wine is a minor thing.
An added note, I was on Amawaterways' Amalegro in 2008 (Danube Christmas Markets) and the free wine with dinner on that ship was even more undrinkable. And it was supposed to be local wines picked up at each stop. Most of the people in my group called it watered down and wouldn't drink it after the first dinner. I found it sour and unpleasant.
Just my two cents. I love good German wine, by the way!