We chose the Viking Homelands cruise to experience an ocean cruise on a "small" ship. We added the Iceland extension. We had taken a couple of Viking river cruses through Europe and had enjoyed the Viking experience. We were not disappointed!
We had some frustrations with scheduling our flights, but once on board the ship, everything was great.
The ocean experience offered larger rooms with adequate storage for our things, more on-board entertainment, more dining options, and health and exercise options that were not available on a river boat. Each restaurant had tables for two, four, and six (and possibly more). On the river cruises, we were usually encountering the same people and found both pluses and minuses in that -- there was some development of cliques. With 10 times as many people on the ocean ship, we were comfortable when staying to ourselves. At the same time, we could enjoy spontaneous conversations with people without necessarily establishing new relationships.
All the cabins offered an ocean view with a veranda. The cabin had sufficient room to store all our luggage and clothing, without the feel of a small room. The room included a stocked refrigerator, TV and safe. Since very little time is spent in the room, we saw no advantage to having a larger room.