Just returned from Christmas cruise on the Danube from Nuremberg to Budapest with a 2 day pre-cruise stay in Prague. A fabulous trip. Sightseeing: Daily walking tours with excellent tour guides.....and of course the Christmas markets. A nice mix of scheduled and free time. All the cities were fabulous, but I particularly liked Regensburg and Vienna. I am a cathedral "buff" so really enjoyed the free time we had to explore. Melk Abbey is not to be missed. Also recommend St. Stephan's in Budapest. My favorite though was St. Lorenz in Nuremberg.
AMA staff: The AMA team was very organized, down to the smallest detail. As a solo traveler I really appreciated that. Peter our cruise manager was awesome. The guy could do stand-up. Optional activities: I did a Christmas concert (on my own) in Prague and optioinal tours of Salzburg and Schonbrunn palace. Loved Salzburg. Salzburgers seem to think Americans are enamored with The Sound of Music movie. Many shops played the soundtrack and had SoM souvenirs, which I found humorous. But the city is absolutely beautiful. Schonbrunn was nice but very touristy, even in December. We were prodded along like cattle. Could not take photos inside the palace and the Christmas market was very crowded. Not something I would do again.
Christmas markets: Each market we visited had its own unique flavor. Some items were obviously mass-produced, but it was also possible to find unique and hand-crafted items. The decorations, sounds, and smells were fabulous and just as magical as I hoped. I sampled nearly everything, including the requisite gluwein.
As for the ship: I had a mid-range priced cabin with a sliding glass door and small balcony. It was perfect for winter as I would not have used the (more expensive) larger balcony. I had a solo cabin with plenty of storage space. The shower was a little snug. Would have been tough for a tall (or wide) person to access, but a very minor thing. The Amacerto staff was exceptionally friendly and very helpful. Every need was met. For the most part I really enjoyed the food. But as others have mentioned, I would suggest AMA consider a "light" dinner option. After touring and shopping all day, I often didn't feel like sitting through a four course meal. Would have been happy with a cup of soup and a sandwich. Otherwise the quality and taste of the food was excellent.....particularly the soups. Yum! Breakfast was buffet style and always plentiful. I usually opted for casual lunch in the lounge rather than more formal in the dining room. Often would eat in town or at the markets.
Entertainment: Something was offered every evening, such as a local folk or singing group. Very pleasant and made for a nice end to the day. Overall: I would definitely do a river cruise with AMA again. And would highly recommend to others.