Aside from a couple pockets of crowds, it was not nearly as bad as I've experienced in the past on NYE. Still crowded, but I never saw a single alert come out saying that entry was in any way restricted (same as I recall from last year although I know there's been some differing of memories regarding closures last year).
There was an interesting issue that I hadn't considered: MP on the app haf a hiccup and stopped displaying FPs as soon as midnight hit.
The FPs still existed (I confirmed with an info kiosk that I still had all 4 FPs and he was able to give me the times for each so I could type a note for myself... I normally screenshot, but I guess I forgot to do so for those) and the system knew they were there, but the app wasn't displaying them.
Word seemed to spread fast to CMs at rides so they knew to tell people to scan their ticket rather than try to find the FP in their app.
The biggest issue I saw with this (beyond that it was holding up a few lines as people who were relying on their phone blocked the scan points trying to locate their "missing" FPs) was that no one could cancel a FP anymore. Ride lines were short and I had 4 FPs booked anyways, but it still was a feature that went away and meant there was zero chance of picking up a cancelled FP.
In other news: I finally got over 1 million points on Buzz! But the system didn't catch it so all I have is my "999,999" picture I grabbed on the ride vehicle. Don't even know what my real final score was. Still a great way to start the new year, though