A few things first. This is a small ship because you have to have a small ship designed to go on the rivers in Europe, get under bridges, and put you into the heart of a city. f you want a 5,000 passenger behemoth with 20 restaurants,different entertainment every night, and a water slid this is not for you. Second, the people going on these cruises primarily want to see interesting places and history. If you want to be entertained 24 hours a day with shows on the ship go elsewhere. Third, it is an older group of people because they have the money and time to do a two week tour. Europe is not the US with access everywhere to the handicapped. Some of the places we went were demanding and require walking. If your felt that they were too demanding you can stay on the ship. But this is part of seeing stuff. I have no idea why the people who travel with Grand Circle are almost all Americans.
The ships, and I have been on several Grand Circle river ships and one Viking (but not a Longship), are all the same. Well designed, comfortable, and beautifully maintained. You never see anything shabby or dirty. The cabins are small, but well thought out. They have an upper open deck with part of it shade protected, and one part enclosed with glass. They have one dinning room which is comfortable and surrounded by windows. There is a very large lounge with comfortable chairs and sofas. The food is very good. I had always thought that the food was just OK until I took a cruise on the Fathom Adonia and learned that the Grand Circle food is actually very good indeed. Breakfast is a large buffet with many choices. They even seem to cook their own pastries - if the don't they fooled me. It never seems institutional. Lunch is either a buffet or you can order off the menu. Lots of choices and most days they have a chef cooking a pasta in front of you. Dinner is ordering from a menu. Ample choices. If you don't like what they have you can always get salmon or a hamburger.
Service is excellent and you quickly learn the staff and they learn what you want. Tipping is suggested but not mandatory and they do a great job - tips are distributed to the entire crew, not just the wait staff. . Beer and wine is included at lunch and dinner although I wasn't crazy about the wine. The cost of beer and wine at the bar is reasonable. They have a package for soft drinks that I like. I don't recall if they have a "happy hour".