I traveled on the River Beatrice with my parents July 2010. We selected Uniworld and the River Beatrice based on what we new about Uniworld's reputation and the newness of the ship and we abolutely loved it! If you are looking for a luxurious hotel on the river, this is your trip and ship. We enjoyed two days in Budapest and then spent the day cruising to Vienna. It was a relaxing day that really made us feel like we were on vacation.
The itiniery, the food, the included tours all worked so well and exceeded our expectations. The ship's staff couldn't have been more helpful and we felt pampered without feeling like it was a pretentious or uptight environment.
Personally I was one of the younger people on the ship which was about 70% retirees but our fellow passengers became friends to us as we enjoyed the sights of Vienna, Salzburg, The Wachau Valley and Passau.
While a riverboat cruise is not a cheap vacation, we found it to be a good value. Our money out of pocket was quite modest once on the ship.
I would highly recommend Uniworld and I would highly recommend this trip -- particularly starting in Budapest.