I just returned from Sunday night's party. I agree with the original OP that the park looked crowded, but there were no waits for any of the rides we went on.
Some things I noticed (having not been before, but having read a lot about prior parties):
1. They are still doing the free family photo, but they are not marked on the guide maps. We had ours made in Adventureland near the Dole Whip vendor - no wait whatsoever. I also saw spots at the Hall of Presidents and in Tomorrowland, but they seemed to have lines all night.
2. The candy spots are noted by big "Goofy's Candy Co." balloons, not pumpkin Mickey heads as I've read about in the past.
3. There was no Liberty Belle Halloween Storytelling Cruise. At the Liberty Belle Depot, you could get your picture made in a Doom Buggy.
4. The "Boo To You" Parade is new. We were told so by CM's, but was also somewhat different than pictures I've seen of previous years. Still pretty cute. The end of the parade is a huge commercial for Goofy's Candy Co. brand.
5. The candy was all "name candy" except for what they handed out along the parade route. When people came along the parade route, DH and I found that they just acted like they put something in our bags, but didn't actually. I thought that was pretty lame - I'd rather you skip me than pretend to do something. (I won't get on my soap box about why I should be treated just as fairly as the children around me...)
6. The "Happy HalloWishes" fireworks display is also good - although I missed just plain old Wishes. I'm not that big of a Halloween person, so I was missing the comfort of pixie dust.
7. In the party brochure, they actually had a couple of hints - one of them being to go to the second parade showing!! Don't publish this stuff!! We weren't anywhere near the route during the first parade, but a CM told us Friday night's first showing was nuts.
8. Most importantly, they're letting people that are in the MK when it closes at 6, instead of being herded over to Tomorrowland, they were giving us the run of the park. DH and I ate dinner at Pecos Bill, rode BTMR twice, Splash Mtn. once, and HM once all between 5:30 and 7:00 p.m. Frontierland was virtually empty - we really saw it balloon in attendance after 7 p.m. If this is the new protocol, I'm really rethinking eating at LTT before the
MVMCP - I'd rather get a jump on the crowds/rides!
All in all, we had fun. We're not big Halloween people, but it was fun to see all the decorations, costumes, and to just do something at the MK that we haven't done in the past.
Any questions, just ask. F&W Fest is tomorrow!!