I've been playing this on and off for the past few weeks, maybe got about 30 hours into it.
The demolisher zombies, ie the ones that blow up and wreck your base, don't get triggered by auto shot-gun/machine-gun turrets anymore. This makes base defense a lot easier when solo.
You cannot out run the vultures on horde night. They move at 250% speed and spit acid like the zombie cops. If you base falls on horde night, your only choice is to stand and fight.
The vultures also do significant block damage if you don't deal with them. On my day 21 horde, there was a swarm of 20 of them above my base. I would occasionally pop my head outside the roof of my base, point my machine gun in the sky and start shooting. There were so many I couldn't miss. Vulture bodies were falling all around me and I still didn't get them all.
The new POI's are a lot of fun (over 175 new POIs) and the crucible is still a pain in the ass to get, but I made it to level 10 intellect so I can craft them now.
Alpha 20 adjusted the "game stage" and "loot stage" mechanics. If you die, your game stage doesn't go all the way back to zero. This avoids the frustration of a stupid death leading to zombie grinding to get your game stage back. I think you lose like 10 or 20 game stage per death, but it doesn't feel oppressive.
The "loot stage" is what determines the type of loot you find (instead of the game stage like in the past). The game stage controls the types and strength of monsters that spawn, and the loot stage is for the types and value of loot of course.
The loot stage is dynamic and based on the biome (location) you are at, the specific POI's you are at, and somewhat based on how long your character has been alive. This means you could raid a wasteland biome building and get decent loot, but if you raid a military outpost in the forest biome you might get better loot because of the difficulty of the specific military POI. In short, the loot isn't only based on the biome.
The random map generator has a lot of nice new features like controlling the size of specific biomes, the amount of rivers that spawn, the amount of roads, etc.
There is a tier of early game shitty firearms available to everyone called "pipe machine gun" or "pipe pistol" etc. They can be repaired with pipes and aren't that strong compared to regular weapons, but they can make a difference early game if you don't want to try clubbing a bear to death.
There are over 1300 craftable shapes now, the game feels more like a proper builder sim now because of this.
Still, the hugest thing about the game is the updated graphics and animations. The game looks so much better even if its not a photo-realistic game like many modern AAA games are going for.
Here's a full list of the patch notes.
https://7daystodie.com/a20-official-release-notes/