This was our first European river cruise, after having been on more than a dozen ocean cruises (predominantly HAL, some Royal Caribbean, and a Seabourn). We sailed Budapest to Vilshoven and were absolutely delighted with the service, atmosphere, food and wine.
We opted for a cabin in the lowest deck, which was "cozy," but totally fine for our needs. Possible drawbacks: closer to the water line, only a porthole for window, and occasional vibration from the engines, and lack of elevator access. That all said, none of those were issues for us and we would seriously consider staying on that level again, for the cost savings.
We found the food to be excellent - always plenty of options and all were well-prepared. Dinner in the "Chef's Table" dining room (no additional charge) was especially elegant.