I can echo the good experiences others had on Friday 10/15. The only issue we ran into was 7DMT going down after we had been waiting in line for 20 minutes...
Overall we had a great time, hit the rides we wanted to ride, saw the new fireworks show, did some trick or treating, ate too much ice cream, drank like 5 Dasani waters, and saw most (all?) of the cavalcades just in our running back and forth. This single event was our sole Disney park visit for all of 2021 so we had to try and make it count as much as possible! Was it worth the $$$$$? For me, yes, but I'm someone who actively despises any kind of crowd and/or line (why do I like Disney, again?

)
Anyway, here are the (excessive) notes I took on what we did:
6:05 - Parked at TTC, walked to Poly and checked out BouTiki to kill some time
6:25 - Took the monorail to Magic Kingdom and lined up in the event queues
6:50 - Let through gates and given wristbands/candy bags
6:55 - Mobile ordered Casey's and quickly ate after sniping a table
7:17 - People Mover (15 min wait, posted 20 min I think)
7:40 - Made our way behind the castle and set up for Enchantment just off of the Adventureland bridge so we would have an easy escape
8:00 - Enchantment (which was
fine I guess, but that's for another post lol)
8:22 - BTMR (walk on, posted 15 min)
8:34 - Pirates (walk on, posted 15 min)
8:58 - Small world (walk on, posted 10 min I think)
9:15 - Trick or treating by speedway (no wait)
9:20 - Fantasyland drinks/ice cream bars (no wait)
9:29 - Space Mountain (12 min wait, posted 25 min)
9:46 - Tomorrowland Popcorn and water (2 min wait)
9:54 - Buzz (walk on, posted 15 min)
10:03 - Trick or treating in scare factory (no wait)
10:08 - Stopped to watch villain's cavalcade in front of castle
10:15 - Shopped a bit and bought our souvenir 50th pin
10:20 - Stopped to watch Jack Skellington cavalcade on main street (totally empty)
10:27 - Stopped to watch Malificent cavalcade in Liberty Square (fair number of people sitting down and waiting for these)
10:40 - Grabbed a popcorn and fruit bar in Fantasyland (no wait) and just chilled for a few mins
10:53 - Decided that the 7DMT line was as short as it was going to get and got in line (posted 35 mins). It broke down at 11:10 so that was a total waste of time...
11:13 - Trick or treating in fantasyland
11:17 - Haunted Mansion (this had a 35-45 min wait ALL night until now when it was posted at 15 or 20 I believe... actual wait 10 mins)
11:35 - Saw Maleficent Cavalcade again while speed walking back to BTMR
11:42 - BTMR (walk on)
11:50 - Trick or Treating in Pecos Bills
11:55 - Caught the last song of the Cadaver Dan's performance
11:59 - Picked up a bottle of water and diet coke for the road
12:10 - There was a slight line for the express monorail so we took the resort monorail and were out of the parking lot around 12:30 if I remember correctly