My wife and I plus another couple planned and booked this trip 18 months in advance. We booked our own flights and transfers as we are very familiar with doing it and it is much cheaper to do so (about half). We stayed in Prague an additional 2 nights and booked that ourselves as well. We were able to get he same hotel and keep our room all 4 nights. We loved Prague, it is an amazing city. Paris, not so much. We found Prague and Germany to be fairly priced, but Luxembourg and France were ridiculously expensive. Several reviewers complained about the buses and time on buses and I agree, there was a lot of bus transportation to and from excursions. BUT, it was handled well and Viking did a great job getting us where we needed to be on-time. We felt that most of the time we had enough time to see what we wanted to see. A few things many reviewers complained about was not enough time to tour on your own. Maybe they were not aware you can opt out of the tours if you are not interested. We did this several times so that we could do our own things instead. The tour guides were local and knew the area, the history and did a fantastic job detailing the area to us. The Voice Boxes were GREAT and an excellent way to take walking tours.
Now for the ship "Idun". Frankly, I was amazed. I was 100% impressed with the stateroom, the staff, the food and the ship in general. The food was very good and abundant. The staff was 2nd to none. The rooms were clean and well maintained. My ONLY complain was the wireless internet did not work well at all. We were in the rear of the ship and the signal was almost nonexistent. In the lounge areas it worked well.
The ONLY complaint I have in general is the long trip to Paris. I would have preferred to skip Paris and spend more two more nights on the ship.
Awesome - what else can I say - truly awesome.
We loved this town. Very good history, great tour.