Took the Christmas cruise from Budapest to Passau. Weather was not the best; overcast all days but one. This is not a viking issue though. Experience was terrific aboard ship. Great food, terrific service and good entertainment. Took only the optional Mozart/Strauss classical presentation. Only 1 1/2 hours, but the musicians, dancers and vocalists were extremely good. Seats not the best and the intermission champagne was below good, but the music and acoustics were great. And no electronics, just pure instrument sounds. Would advise it.
Back to the boat though. The selections at each meal were varied and all great except only one night with German sausages that was only good, not my preference. All activities were explained, on time and reviewed the evening before. Very helpful. The free morning tours were usually good with some gaps in the walking tours. I especially liked the service that Viking provided for airport transportation at the beginning and end of the trip. Convenient and timely.
The Christmas bazaars got to be redundant after the first two or three, but not under Viking control.
Very small but clean and reasonably priced. Did not spend much time there except to sleep and prepare for activities. Based on this trip, I will not purchase a more expensive room unless it is necessary.