I have to say we were a little apprehensive of the "O" class ships (Marina and Riviera) as we have only cruised on the 3 other R class ships. We thought we would be overwhelmed with the numbers of persons. We both were pleasantly surprised that is not the case. Oceania has a winning product with their new ships.
Service - Excellent
Food - Excellent
Staterooms - Nice and spacious and better overall than the R ships.
Crowded feel - NOT AT ALL. All of the dining venues always had plenty of empty space. Not very many lines and we did not have any issues when tendering. Only pet peeve was the elevators. There are not enough - especially AFT where the restaurants were. This was compounded the last few days when two of them broke.
Bars - this was not a drinking crowd. Bars including Martinis were empty even during happy hour. Usually you have to fight for a seat in Martinis on the R ships.
Air and Venice: We booked our own air using FF miles - MCO-EWR-FRA-Venice. Almost like an Oceania routing with lots of connections. Crew was late in EWR missed our connection in FRA so instead of getting to the hotel at noon we arrive at 6pm. We did not have any issues with luggage as we both did carry-ons to Venice.
Booked into the Hotel Londra Palace in San Zaccaria for two nights. We used the Alilaguna shuttle and this was crowded but OK. Hotel was a bit pricey but certainly better than Oceania's price and about the same if booking the Hilton directly (about 300 Euro). Advantage --close to San Marco and excellent service.
Embarkation: We took the Alilaguna from San Zaccaria to the Martima Station. Riviera was using Terminal 107 as Oceania usually does. Arrive at 11:30 and we were checked in an up in the terrace for lunch in 15 minutes. Very efficient. Did not get the clear to go to rooms until 2pm (a little tardy but understandable)
Stateroom: Concierge in 10092. Found the room roomy compare to the R class. Mattress and linens by far the best of ANY cruise line. Our impression was good usual complaints. Shower - too small. Not enough storage,. The number of drawers was really tight and we did only carry on.
Food: Of course Oceania excels here and no exception. Excellent 5* all the way - from the MDR to the Terrace no issues with food or service.
Best was La Reserve. Food and pairings were excellent - we did the Discovery Menu. Surprised about the availability of seats (no issues) 1 tables were filled for the first and we even considered doing a second as there was availability for the last one.
Toscana was excellent - my wife usually rates this one low but she enjoyed it.
Red Ginger - surprised as this was everyone's favorite -it was not ours. Found the food lacking as maybe I used to eating excellent Asian cuisine and this "fused" Asian was just not real.
Service: I have read in the past about complaints on Riviera about service in the Terrace. No such issue during our cruise. The service was good the Head masters were certainly doing a good job of supervising the staff. Service in the rest of the ship was also great. Our favorite Assistant Waiter on Nautica (Mr. Chua) was promoted to a Full Waiter and was working in Red Ginger - again he treated us like his parents and certainly was surprised he recognized us.
Entertainment/Enrichment: No comment as we generally find anything here as lacking. Only exception was the String Quartet and our favorite Gavin the Piano player in Martinis. He was funny and personable - much better showman than any of the dancers, singers and comedian/magician on the ship.
Guest Lecturer - where does Oceania find these people? We had a PHD in History who expertise is Russian and Alaskan History giving talks on the Byzantine, Venetian, and Turkish Empires and did not know the basic facts on where the Venetian's stole the body of St Mark from.
Complaints and Pet Peeves: (and there were few)
1. Elevators. Poorly designed with long waits for elevators. Should have 4 in the AFT many were using that way to get to MDR, Terrace, Toscana, Polo, and La Reserve. This was further complicated toward end of cruise when 1 elevator in Mid Ship and 1 elevator in aft (that serves the dining) were broken. Also the elevators design is poor with a control panel only on 1 side. Certainly Oceania should have paid the extra few bucks to have a second panel on each elevator. Makes it difficult for guests when crowed to select the floor.
2. Windows - the ships windows were always dirty. (only two tendered ports so there was no excuse for this)
3. Terrace cafe - Seating there is too tight. Restaurant was never full but the table layout and number of them made dining uncomfortable.
Disembarkation: Departed in Istanbul at 0830h. Many passengers had Oceania air and had to leave the ship at 3am to catch there 5:30AM flights. Disadvantage in booking without a deviation is you have to connect through Europe and you need an early flight.