On our recent voyage on the Marina my wife and I were very pleased with the general layout of the ship as well as the dining choices. We found the steak house and the Italian specialty restaurants to be excellent.
Two design flaws detracted from the experience. First, each cabin has a tub and a separate shower. That sounds like a benefit, except that making room for the tub necessitated making the triangular shower infinitesimal. Not one fellow passenger that I spoke with even considered using the tub. The designers should have omitted the tub and fashioned a decent size shower. Second, the wifi system (when used in the cabins) is very weak. Even the ship's computer guru admitted that guests needed to come to the computer center to get a good signal. For a brand new ship, such performance is very disappointing. Again, the designers should have done better.
A last word about tours; Although not unique to Oceania, the prices of their tours are very high. For example, a tour of Florence and Pisa (admittedly a long, 8 hour day) that included NO admissions at all was over $200 per person. We had to pay our own admission fees to the church and baptistery in Pisa, as well as the one church in Florence that we had time (during lunch "on our own") to visit. Paying a premium price for a premium excursion is fine. Paying a premium price for a less-than-ordinary excursion is unacceptable.