This review is on the River Princess page because that was the designated boat for our Authentic Danube and Prague cruise. But, at the last minute, the boat had a mechanical issue so a substitute called "The A" was used. The point is that with river cruising you have to be flexible because anything can happen. Unfortunately, The A was certainly not the luxurious atmosphere we thought we were paying for, with plastic seating in the sparse dining room, numerous drawings of naked women in the hallway to the rooms, tiny cabins, and generally hard and sterile surfaces everywhere. But we did get our River Princess crew, food, and excursions, which were all very good.
Following are a few comments about river cruising because there are things we did not expect. First, on the Danube there are locks. A lot of locks. One of them was 83' deep! When you go into a lock and the water drains, you are very close to the concrete wall (you could reach out and touch it - but don't do that). There is a certain odor, somewhat sewer-like, from the wet, slimy, and dripping wall. So because the air conditioning didn't work in our room, and it seemed to be stuck on too much heat, we wanted to have the window/door open while sleeping, but we couldn't because of the smell. So we were quite hot most nights. Also, the smell can occur while docked when they are pumping out their tanks.
Second, the upstairs roof area was mostly closed. We traveled in October, so it was somewhat cold. The enclosed bar on the roof never opened the entire time we were there, and only occasionally could one go up to view the scenery, etc.
Cabins on the substitute ship, The A, are even smaller than on River Princess. It was tiny but the bathroom was better than expected. I would think the same for River Princess. Our AC did not work, it was stuck on heat. We requested and received lighter-weight bedding, which helps, but for a mid-50s female, it was too hot to sleep.