We were a family of six non-German speakers including two kids who had a very relaxing time on this trip.
The itinerary was supposed to be south to Switzerland but when we boarded we found out, because of water levels, the boat would be going north. This was disappointing as members of our party had recently been to the cities to the north and we had specifically wanted to see the Alps and that was why we picked this trip, but we ended up having a much more easy trip as we only spent about two days in port, therefore giving us lots of relaxing boat and family time. Also, we got a 50 euro credit per adult to use on board so we all had massages.
We had booked this trip via the North American offices and got mostly great service but also some wrong information (e.g. about disembarkation, facilities).
The information on the boat via the loudspeakers was exclusively in German. We sometimes asked the cruise manager to tell us what an announcement had said. We did get lots of information in English in our cabins. We didn't do any excursions because they were all in German only. The signs were only in German as well so we may have broken a few. But if we asked for help we always got it. The staff were lovely. Some were clearly not comfortable with English but the ones that were seemed to go out of their way to make us feel welcome.
The hot tub outside was nice and not too many people used it due to the cold temperatures in January. The sauna we never quite got up the courage to go in as it was nude and for both sexes. The gym didn't have too much (it is not a big boat) but was fine.
The boat spent a lot of time docked right beside another A-Rosa ship, meaning that for long portions of the trip half the boat had no view, which was too bad as we had paid extra to have rooms with Juliet balconies.
The food was really great with lots of options vegetarian and otherwise. We loved all the virgin cocktails. Only two beers were part of the all-inclusive but they were good. Our large party sometimes couldn't sit exactly together at meals if we didn't get there on the early side but mostly it was fine. Mealtimes were not too chaotic and it was a pretty elegant but not stiff atmosphere.
The ship was very clean and nicely decorated. Our cabins were well-designed with lots of nice storage.
Two of us did feel ill the last night (and one was ill for a few days after that) so we don't know if it was something we ate or something else like a virus. Everybody else was fine.
There were no specific activities for kids and just a handful of kids on the boat but we played games and did the hot tub and socialised. The staff were kind to the kids.
In summary, this is a very German cruise line good for a relaxing time.