We did the party on Jan. 26. It was very cute, great fireworks and parade, fun entertainment. Lots of treasure spots to get beads, chocolate, and raisins. Little to no lines for rides. You can get into the park at 4 or 4:30 and stay until 12:30 so it is good deal compared to a 1 day ticket. We saw some characters, like Cinderella's stepmother/stepsisters that we haven't seen before. The character lines seemed long, but that seems typical.
My only downside with kids age 9, 7, and 3, is that it was just too late for our kids. They had taken a nap in the afternoon so they were fine for the party, but we didn't get to bed until 1 am and they were a total mess for the next day. Truly, beyond exhausted. I wish we had just hung out at the hotel for the day.
So, I would do it again but do nothing the day of the party until the party, and then do nothing the day after. But then I'm not sure if I would want to give up 2 days of regular park time to go to the party for 1 night.
It was fun though...