There were a few of us who went off on our Christmas Market River cruise, all different ages, sexes, married & single. So between us all there should be lots of different opinions.
I really liked it, and would definitely consider a summer cruise, I think it would be so relaxing and laid back to sit on top deck and watch the world go by. There is not much not to like, and it can cater for all tastes. They usually dock overnight in the different stops, setting off in the early hours of the morning so by lunch time you are ready to get off again to explore. During our stop in Cologne we came back and had dinner, then wandered off to investigate the nightlife in Cologne. There are restaurants and bars all within a 10 minute walk from the river side , no need for taxis!
There is an album of pictures you can browse go to https://www.facebook.com/teresa.esberger and take a look, any question please ask.