There a multiple stairs which may be challenging to travelers with difficulties climbing. The popularity of the Danube requires ship to double tie which proved fine for the bottom cabins but was unpopular with those who had balconies on the main floor. There is very little privacy when docked.
I would have appreciated an occasional coke away from meals but that is a very minor issue. The ship was very comfortable and enjoyable to be aboard.
Although we really enjoyed the cruise, it was drastically noisier then I expected at night. Going through all of those locks on the Danube was noisy. If you are a light sleeper, I would suggest a different cruise