Good and bad, mostly good.
Good = a clean, quiet ship; every meal began on time; meal servers efficient, attentive -- ready with coffee refresher, ready with a second glass of wine or beer; meal portions sensible; food tasty, nicely presented; breakfast buffet variety of items (cereals, eggs, omelets, sausage, fruit, croissants, jams/jellies, OJ, grapefruit juice, coffee, tea, butter, honey, etc.); 24/7 quality coffee from a dispenser near the lounge; treats (cookies, pastry) always available by the dispenser; sanitary standards obviously a priority, from your room to the hallway to the lounge to the restaurant
Bad = tours to Salzburg and Durnstein too much emphasis on shopping -- not worth the 2-hour trip to Salzburg, although scenery was beautiful; Salzburg bus dropped you off just outside the main shopping district (don't believe the Web and brochure of the Salzburg gardens because it is only about two blocks long and a block wide) and although some free time was available to get to the hilltop castle there was not enough time to actually stroll into the city proper to see neighborhoods and other city life; Durnstein was one long, narrow street packed with touristy shops, with the ancient castle perched above, reachable by a hike on a steep trail, which actually was good exercise; my advice is to skip Salzburg and stay in Linz to see the city there and you'll have all day to do it; conversely, not nearly enough time in Vienna, only a morning tour with afternoon free time -- it's a city worth part of another day, which could be accomplished by leaving Durnstein off the itinerary and just docking in Melk, with its beautiful abbey.
Good = some of the local tour guides who actually were informative because they mentioned modern life in whatever community we were in (Bratislava, Budapest, Passau) with details about the economy, housing prices, political conditions -- in addition to the usual history info.
Bad = some of the local tour guides who stuck to a script and did not deviate, had almost no sense of humor or otherwise put no personality into their talk (Salzburg, Vienna).
Good = free time in Passau and Budapest to explore the cities on your own, get away from the tourist areas.
Bad = not enough independence allowed you, because we would rather have gone off on our own with a good local sightseeing book rather than being stuck in a slow-moving group.
Good = attitudes of ship's crew, servers, program director and assistants, concierge; all to be expected, of course, because their livelihood depends on it, but still pleasant to encounter.
Bad = attitudes of too many fellow passengers who never tipped the local tour guides or bus drivers; this is inexcusable because that's how these people earn extra income and saving a few euros a day by not tipping just so you can pay for the extra booze you want is awful.
Good = We did our airline travel, and we would recommend it because you can rest a day before your cruise and you can continue to where you want to go when you want to go. However, even though we booked our own flights Viking made sure we had transportation (we paid for transfer from Budapest hotel) and a Viking representative met us at the airport as the sun rose in the sky to make sure we got through the baggage process. Viking doesn't forget you when you leave the ship.
Would we go again? A couple years from now. Meanwhile, what we learned was how to plan our own trip at less expense. We took trains before and after our cruise (this was a dream vacation that stretched to 22 days) and now we feel comfortable navigating Europe (English, French, German trains).
Our ship was first to arrive at three cities and at some point during the evening another Viking ship docked alongside, wiping out our river view. This was especially irritating in Budapest with its grandeur and magnificent views.