The Xmas cruise was great! I thiink the season elevated everyone's sense of well being and friendliness. Formal night was Xmas Eve, Santa was in the main lobby, characters all over the ship. We only wish the temps were a bit warmer - only low to mid 70s the whole week.
The 2010 NYE was a blast - very high energy. There is a big NYE party on deck with live music, characters, fireworks, buffet, etc. We were told they normally do the fireworks for the Pirate deck party (the night before), but on the NYE cruise they save them for NYE. Our favorite feature of the NYE cruise is 2 days at Castaway Cay.
I understand the 2012 NYE cruise will be the last one that stops at CC twice. That itinerary has been dropped from the 2013 schedule.