The Good - Prague pre-trip at Hilton (make sure your room has been recently renovated), Regensburg/Vienna/Budapest attractions, the European winter markets, excellent service on the ships, flow of wine/beer at lunch and dinner. Good food and some regional.
The Bad - Viking has been busing their customers since summer due to low river levels. Corporate offices have known about this, yet continue to sell these trips and will not confirm this until 2 days before departure. The result is shortened or rescheduled shore trips, missing many cruising days on the river, and continued unpacking and packing. Per the other US reviewers, without threat they generally will not refund you anything to compensate for the loss of service, but may offer you a dollars off coupon good for another cruise within a year. We were supposed to be on the Tor, but also were bused to the Var, and finally the Bragi -- permanently moored in Pest. If you opt for the cheap Viking air, you likely will be on the most inconvenient flights. On the return trip, we we traveled for 30 hours, flying Budapest to Paris to Seattle, then back to the Midwest. They offer some flexibility for a $50 fee to some but did not offer this to us.
Advice - Do not book this trip or perhaps other Viking European river cruises in 2018. If you must, don't bother to book an expensive upper level room, as you will not be opening your balcony in the wintertime (nor will you be cruising the promised Wachau valley for instance). Do not buy the Silver Beverage package, as you will be on a bus during some days and some evenings, not in the bar enjoying the view. Free drinks on the Bragi if that is your last day. Know that tipping is supposed to include the tour director (unknown on our previous ocean trips with multiple lines), although ours (Violetta) was quite excellent and hard working.
Good bed, excellent cabin stewards, lots of cabinet space, fridge. Tight spaces, but what did you expect on a longboat ?
WWII tour worth the extra if you want to see more of the Third Reich.
One of few unbombed WWII sites with lots of charm and walking fun.
Bus ride into town
Much history and class.