I was part of an alumni group of 19 people who sailed together. The pre-cruise package in Prague was attended by all but two of our participants. That add-on was worth it and the quality of the Prague Intercontinental Hotel and Czech Republic tours was well worth it.
The water level on the Danube was low so we were not able to embarkation was moved from Nuremberg to Vilshofen. The embarkation process was very well organized. Our cruise manager did a great job in organizing similar if not identical experiences. By Tuesday, we were back to a normal schedule.
Dining (including wine and food) was top notch. I found the dining room staff to be very hospitable and the food (both from the buffet and from the menu) was delicious and offered enough assortments to keep the experience feeling fresh.
My cabin was comfortable and I didn't mind the fixed windows at all -- in fact, I spent so little time in my cabin that I'm glad that I hadn't upgraded to a balcony room -- I found the lounge, sundeck, and other public areas more than adequate.