We were fortunate to have one of the Owners Suites and they are beautiful and certainly worth the cost if you enjoy having nice accommodations on board the ship. The storage is outstanding in the OS as you have 3 floor to ceiling closets as well as several other compartments for storing belongings. We didn't find being in the back of the ship at all uncomfortable and used the huge veranda often, even when we were at sea. Our butler, Friedrich was very attentive and helped make our trip enjoyable.
We enjoyed both of the specialty restaurants. My wife preferred the Toscana and I the Polo Grill. Both provided attentive service and the food and selections were more than adequate. The meals in the main dining room were very good as well. We did not experience the Tapas.
The staff on the ship is friendly and seems to care about providing good service. I can not recall one incident where the staff was not fully capable, friendly and service oriented.
We didn't attend any of the entertain performances, but we did enjoy having a 8 piece band play on the pool deck during some of the afternoons.
All in all - we had a very positive experience. We are not able to even mention any negatives other than possibility expecting a bit more perks as a suite guest. But that is relative and would not discourage us from enjoying another cruise with Oceania.