We were a family of 4 (kids 13 and 15). The reason we chose Radiance was due to the teenage kids club and the number of dining options (my husband is a chef and food quality is important to us). We pre-booked the Chef's Table Dining Package which cost us $114 each (adults only) This gave us 5 extra dining options.
Boarding was easy, we were supposed to check in at 2.30pm, however when we dropped our bags at 1pm I just asked if it was possible for us to board and they said 'no problem' so that was a good start. When we boarded we went straight to our room which was located just meters from the Guest Relations desk, at first we were concerned as we had booked a quad and it was set up as a double, however this was changed at turn down. We spent the first night as the double bed with the 2 single beds dropping down from the ceiling on either side of the cabin (directly above the double bed), but this didn't work as the only way out of the double was to crawl down the middle of the bed. The next day we asked our attendant to change it to 4 singles and this was much better as it also gave more room. The cabin was better than we had anticipated.
The first 2 days were wet and rough so we all spent them being seasick, my husband and I just felt queasy all the time but our daughter was sick all day and our son a couple of times. We took all the medication possible, the complimentary tablets from the desk seemed the most effective. Reaching Noumea was a relief.
Cabin 4551 was very close to the main Centrum which was where a lot of the entertainment happened, also close to the Guest Relations desk. It was still very quiet considering and only on 1 occasion was I awoken from noise at 11pm in the Centrum. The room is perfectly fine with lots of storage (just enough room for 4, would be plenty for 2) As a room for 2 it is very generous, as a room for 4 it was tight, but not uncomfortably so. My only negative is that the two pullman beds (a single that comes down from the ceiling) made the 'double' bed too uncomfortable, the only way to get in/out of the double was to crawl down the middle, so after one night we asked for the double to be split into 2 singles which gave us so much more room. We moved the little coffee table into the wardrobe to also give a little extra room. Being an interior it was lovely and dark at any time so daytime naps were easy. Bathroom was clean and ample space for 1 person at a time, just had to be careful when showering that water didn't go everywhere.