This was our first river cruise and was chosen to visit countries and cities we had not visited before.
The Vili longboat was excellent but beware of booking suites with balconies or French windows! There are over 60 Viking longboats cruising and often when they berth they tie up alongside an identical boat. This means that when you open the curtains in your cabin in the morning you are looking into an identical cabin window about a metre away! Our cabin on the lower deck was excellent
Also be aware that there are over 60 locks on the Rhine/Main/Danube between Amserdam and Budapest and also many low bridges - this means that the sundeck is closed for 5 days in the middle of the cruise!
Excellent though a bit small, but to be expected on a longboat