Just completed a 25 day Pea rls of the Orient Cruise with Oceania.
We booked the full package with Oceania to include flights which we were able to upgrade, hotel JW Marriott Beijing and Shangri La Bangkok at the end of the cruise. Oceania provided transfers to hotels and to airport.
Nautica is the sister ship of the Regatta a ship we have previously sailed on with Oceania however we noticed a difference in the service provided on the Nautica and this was mainly due to their ability to deal with my coeliac disease which requires a gluten free diet.
Cabin was fine but not really worth purchasing Concierge level if you can get a balcony cabin on floor below.