We were at the party Thursday night. It did feel a little crowded, but I have no basis for comparison except for during the days.
I think the main issue was that Haunted Mansion and Pirates were both down and it pushed people into other lines. The main thing my DD wanted to do was 7DMT and the lines were over an hour much of the night. We were able to ride during/after the second parade, but it was a 30 minute wait both times, which I wasn't expecting during the party. Trick or Treat lines were much more manageable later in the night. We walked right up to three different locations near the end of the night, but we saw long lines at other times.