This was our first cruise with Viking and we took the City of Lights cruise on one of the longships. It was incredible from the minute you arrived. The staff (especially the program director) were very attentive and you wanted for nothing. What's not to love about being in Paris, all through Germany and Prague. The hotels we stayed in on both ends (as this was a tour with 2 nights in Paris and 2 nights in Prague with city tours included there) were gorgeous and on your own you can easily get around town. The food on board the ship as well as the cities we visited was all amazing. The ships chef really outdid himself and I would give each nights dinner a 5 star rating. One good thing is the tours kept you so busy and there was so much walking, we didn't gain a pound on the entire trip which shocked me.
Be prepared with good walking shoes as most of the areas visited had cobblestone streets and not easily manipulated without sturdy comfortable shoes. The entertainment on board was limited since it was such a small ship, however quite good and honestly, we didn't see much as the tours wore you out so going to bed
early is what we did most nights. Going through 36 locks on the Rivers, Mosel, Rhine and Main were very cool. Make sure to get a room with a balcony so you can enjoy the experience of the locks first hand.