We went Halloween night in 2002.
Yes, it was very crowded. But we still enjoyed it and had a great time. We loved the atmosphere and just being at MK for Halloween!
I can't tell you much about the rides because we focused on trick or treating, the parade, and the free photo. Yes, the treak or treat lines seemed long but they went VERY fast and it didn't seem bad to us.
Yes, there was too long of a wait for the Princesses at the Carriage behind the Castle but that didn't surprise me in the least.
We ate at LTT, got first in line for the free photo right across from LTT and then did one trick or treat station on our way to Haunted Mansion. No wait for Haunted Mansion. Then we continued trick or treating through Fantasyland to Tomorrowland and then to Toontown. We stayed in Toontown and rode Goofy's Barnstormer 2 times in a row with no wait. It was packed though but we just loved the atmosphere.
Then we headed back toward Fantasyland and it was now really packed and we couldn't do rides there. By now it was almost time for the fireworks. Our DD got very sick going into Fanstasyland so we spent our fireworks time there cleaning her up and getting her a new outfit. Then we headed to Main Street to get a spot for the second parade. It was already pretty filled up but we got one of the last spots. We probably waited 1/2 hour for the parade.
Then we had to leave because our DD was too sick to stay any longer.
I only have
MVMCP and off-season to compare the crowds to and it was by far more crowded than either of those times BUT we still had fun and we are going again next Halloween night in 2004. Our DD wants to go again NOT SICK!
If I were you, I'd go check out the Halloween thread up top and read some reports. Some people speak of no waits for rides depending on where you went...like Frontierland or Adventureland. We never made it to those areas so I can't say how it was for us.
Have fun planning!