I had experience with Viking on their river cruise from Budapest to Amsterdam, which I must say was one of the best trips I've ever done. I was impressed with their high standards of quality and their seamless organization, but this was my first ocean cruise with them. I've done other ocean cruises, both big ship and small ship, and Viking wins again, hands down.
The ship is beautiful. Since every cabin has a balcony there is plenty of room inside for other amenities: restaurants, bars, lounges, quiet little nooks with seating and books, and something I found very useful, a free guest laundromat n each level. The pool area has a sliding cover, so even on chilly or wet days you can swim or just sit there and read.
I really loved the in-cabin information on the flat-screen TV, with a bow camera and a map. I took pictures of the screen every morning to help me organize that day's photos.