We chose this cruise based on our satisfaction with 3 previous Oceania cruises and for this cruise's ports of call. There were high points and low points during the cruise, unfortunately with too many lows. The main problem was too much time at sea due to the 2-day crossing of the Tasman Sea plus a 3rd day that was onboard ship when it visited Milford Sound enroute to the east side of NZ. The seas were often rough, and Sirena (as one of Oceania's smaller ships) really didn't cope well with the rolling waves even once we reached the Pacific Ocean side of New Zealand.
Oceania's cuisine continued to be excellent, although we couldn't enjoy several dinners as the ship was rocking and rolling. Red Ginger remains our favorite, as it was on Marina and Riviera. The Tuscan Grill is also good, but we thought the menu succeeded better with its grill selections than its Italian ones.
Although we had previously cruised on the same-sized Regatta, and later cruised on Marina and Riviera at the concierge level, we found Sirena's concierge level cabin to be too small for our comfort. The small bathroom and tiny shower were especially disappointing.
The cabin is much smaller than on Oceania's Marina and Riviera on which we had previously cruised. The bathroom was very small and the shower stall was tiny even for a smaller-than-average-size man like myself. We also had a problem with air and rainwater "leakage" around the sliding door to the veranda. Maintenance couldn't fix it until during our 3 days at sea and then they had to wait another couple days to get to a port where we would be docking. The eventual fix was a great improvement but not perfect.
On the positive side, the bed was very comfortable, and the housekeeping staff were excellent.