We just got back from Disney and went to the party on 9/22 which was a sell out and I have to say it was absolute chaos.
Cast members were enforcing bands pretty strictly (we saw a bunch of people get escorted out multiple times), but the amount of people in the park was still overwhelming.
We spent a total of 3 days in the MK and we felt the crowds were by far worse at
MNSSHP vs the other days we were there. I'm not sure if the crowds were just more concentrated at the party (Main Street was like something out of a claustrophobic person's worst nightmare) or what but i can tell you it was literally elbow to elbow packed in like sardines crowded.
We got to the park around 630, got some pictures near the entrance, met talking Mickey and tinker bell (we had fast passes) and around 7 headed to haunted mansion where we waited about 25 minutes to ride. We then rode dumbo (walked on) and After that we went to get our Dessert Party lanyards (more on that later) and attempted to head down to Main Street to get to our "VIP" Section for the boo to you parade. It literally took 35 minutes to get from Dumbo to town square. People were just grid locked and not moving- not because they weren't trying but because there was just no where to move to.
By the time we got to our VIP section (which was the circle around the flagpole in Town a Square) it was 8:35 and the parade was about to start. We waited about 20 minutes for the first float to get to us and by the time the parade ended it was somewhere around 9:15 and we were escorted by cast members to Tomorrowland Terrace for the dessert party. I was thankful we had them as they cleared the way and we got to the restaurant quickly.
We had some pretty tasty desserts and had a fantastic view of the 10pm Fireworks.
We ventured back out around 1030 in hopes of riding some rides or meeting some characters but the lines at that point were absurdly long: 45 minutes for space mountain, 35 for Peter Pan, 90 for 7DMT. Most character lines were also super long and were being cut off.
We gave up at 1115 and headed back to the resort.
I think the dessert party saved the night from being a total failure for us. My almost 3 year old really liked the parade and was mesmerized by the fireworks but there's no way we would have had a good view of either without the dessert party upgrade. So while it was a fun night, it was not $300 fun which is what we paid between the dessert party upgrade and tickets for the event.