We have done 3 river cruises and 2 ocean cruises with Viking and have enjoyed all of them. The shortest was 9 days and the longest was 23 days. I don't know how the entire staff knows your name from day one. The crew can't do enough for you. We booked another Viking cruise before this cruise ended and we left the ship.
One of the more enjoyable experiences for us, is having a cocktail in the Explorer's Lounge looking out over the bow of the ship. Another nice feature is the multiple dining options ranging from a sit down dinner in Manfredi's or the Chef's Table to more casual fare in the World Cafe.
The shore excursions give you multiple options to explore. The included excursions, which last about 4 hours, are always well organized. The guides speak excellent English and are very knowledgeable. The optional excursions can be as long as the whole day. Always worth the extra fee.