Uniworld is great! My wife & I spent 2 nights in Vienna pre cruise, then boarded the River Ambassador which stayed overnight in Vienna to give us another full day before sailing upstream on the Rhine. From the time we boarded until the end we were greeted by an ever gracious crew who really paid attention to every detail. I can't say enough about how good they were. From the first happy hour in their well appointed lounge area, the staff not only remembered our favorite cocktails, but would warmly greet us as we walked in, asking if we wanted a "Dewar's and water" or a "Vodka Tonic". Drinks and wine are included and we never had to ask for another, since they were right there anticipating our wants and needs. (I've found slow service on other "all inclusive" trips or where we've already paid for a beverage package.
The very small stateroom (128 sq ft) was the only reason to give it 4 stars instead of 5. The River Ambassador is Uniworld's smallest ship (120 passengers) and it looks like the staterooms on their other ships are larger-we could have used the additional space. However, the housekeeping staff did an excellent job of keeping it spotless every day and night. Laundry service was reasonably priced and service was same day, depending on when we left the bag out.
Food was as good as we've ever had on any ocean cruise, including specialty restaurants. Breakfast and Lunch buffet provided plenty of choices and variety (example meat or veggie lasagna when they had lasagna), along with the usual salad fixings. Dinners offered a different menu every evening, and the staff was always there to refill your wine glass. The house wines changed every day and seemed to be local.
Small, but comfortable in every other way