No matter how calm an ocean is I get seasick because there always is a swell - a river cruise is perfect. My husband and I and our 2 sons (adults - not young children) were on the cruise (we always take them so they can be tour guides and we tag along) Our suite was very comfortable and the room staff were terrific.
I have food allergies and the Maître d' gave me a menu every morning of the meals for me to choose from and ensured that my choices were free of the allergens (sometimes being specially made) and served them to me personally as well as serving our sons who are vegetarian.
Excursions were very good for the most part with most having 2 or 3 choices for difficulty of walking. Buses from the ship to the start of the excursion were sometimes parked in very difficult places entailing long treks to and from the buses to the start/finish of the excursion -- but you can't have old European towns and cities and big streets. I liked the use of local guides because they were so enthusiastic and informative. The ship's cruise director was phenomenal. I would take the same cruise just because of her; however, we are getting old and decrepit and have a lot more world to see so need to find another cruise.
The biggest downside were the 50-plus locks that we had to go through which put the schedule way off at times. Prague was a gorgeous city as is Paris - It would have been nice if we could have actually embarked and disembarked in those cities - the cruise was in fact a cruise of Germany.