We were on the Wonder this last year for a five night cruise departing 30 Dec and had a wonderful time. The 31st was our Castaway day, so that may have made things a little more low key. They had a sort of "gala" menu in the main dining rooms. We were first dining so it was a bit odd to have half the people on the boat heading off to dinner all dressed up while everyone else was still wandering in wearing shorts and beach wear. Then there was a special early New Year's dance party with the characters in the atrium at about 7 or so. They did a count down with lots of fanfare and confetti which did a great job of convincing my preschoolers that they'd really stayed up until midnight.
They also had the fireworks that night which were really special, but I don't know if they are able to do that if they're at another port. There were parties and activities going on all night but my little one wasn't feeling well so I had to turn in at about 10 so I missed that part.
When we got on the decorations were all up and there was Christmas music playing throughout the boat but that stopped quite abruptly on the morning of the first. Everything came down over the next day or two. We didn't mind; I tend to take my own decorations down about then. But it was odd to go to the parks the next week of 4-11 Jan and find that all the Christmas stuff was still up and there were Christmas carols everywhere. So if you want pictures of the decor or the characters in their Christmas outfits, do it before the 31st! Hope this helps.
