We have taken 6 Viking River cruises but this was our first ocean cruise with them. Cabins and public areas are lovely; free Laundromat is wonderful; Wi-Fi works well; staff was very polite; entertainment and lectures were fist class; food fabulous. However, time in ports especially Athens and Istanbul is VERY limited. If you have not been to these cities, (or Venice) extend your trip in Istanbul and/or Venice and take a day long tour in Athens. Included tours in those cities are "superficial" to say the least.
Full day Santorini tour was a waste. We had lunch in a lovely restaurant and then stayed over an hour for Greek dancing. Would have rather seen more of the island. Walking in Santorini is not for anyone with physical challenges- many, many stairs. The surprises were Kotor, and Dubrovnik- both had good included tours. Many times, we could not just get off the ship unless you had a booked tour and many of these started quite late in the day.
Wish someone had told us about booking restaurants on ship. There is no fee for Manfredi's and the Captain's Table. Book these ahead (if you have an expensive enough cabin) or as soon as you get on the ship if you have a cheaper cabin. I did feel that everyone should be treated the same and that some should not have privileges such as pre-booking of restaurants.
Lovely but could not hear announcements in cabin. Bathroom is so nice and has heated floors.