Ours was one of many river cruises affected by low water levels on more than one river, but we'd live in Germany during a drought year back in the 70s so weren't concerned. Leaving Amsterdam a day later than originally scheduled gave us another day on our own (Heavy rain would have made tulips + windmills most unpleasant.) and we had one well-organized and well-predicted ship-swap. The logistics of the ship swap were impressive: moving two boat-loads of guests by luxury coaches, moving luggage by truck, cleaning, rescheduling meals & shore excursions.
Local guides (required by law) extremely knowledgeable -- don't be afraid to book your day full. Because we had a 2nd primary Viking staffer, tours eventually split into two groups to accommodate those less mobile (bus access to central town areas limited by ordinances & cobblestones = cobblestones) -- to everyone's benefit.
Notes in no particular order:
1. Vienna moorage within walking distance of the Prater park & the giant ferris wheel -- the Wiener Riesenrad -- from The Third Man movie.
2. Cologne: Schokoladen museum
3. Passau: St. Stephan's organ concert but wish we would have had time to purchase a CD from the gift shop -- get into the church as early as possible for best seating
4. Wachau valley winery tour -- source of many Viking's wines
5. Historical Bavarian village -- added mid-trip
6. Bratislava by night -- extra evening attraction
Crew very willing to answer technical questions -- we're boaters ourselves -- staff diplomatically dealt w/passenger not interesting in enjoying the cruise other than ruining everyone else's day.
Things not explained:
1. If you're not in a dining room by "door closure," you don't get dinner.
2. Purser's office doesn't like to change paper money into coins for tips; they suggest using ATMs which don't give coinage.
Serious problem: wasps (yellow jackets) everywhere on shore & on the boat, esp any place where food/drink (They love beer!) served. We suggested wasp traps after I'd gotten stung on a shore excursion; didn't dare a second sting since the boat doesn't carry an Epi-pen (My doctor said I shouldn't need one if stings infrequent.)
Post-cruise comments directly to Viking, including compliments, met with cliches. We'd booked directly through Viking, not a 3rd party, and eventually learned that other depts (air travel!) would make up answers rather than admit lack of knowledge.
Viking's low-water advance-alert email offered a 50% credit vs future cruise, so we'll be on an ocean cruise this fall while considering additional Viking cruises -- including maybe this one from the other direction.
Rarely in the stateroom except to sleep but nice not to feel like we were sleeping in the living room. Lots of elbow & "staging" area when planning for next day's shore excursion or coming back after a busy day and getting ready for dinner.
Small drawer./shelving area in closet 90 degrees fm web page diagram, eating into hanger space.
Could use at least one more USB and one more power (either U.S. or European) outlet.