NPCs, when knocked down, don't get back up unless hit by a car or are otherwise attacked to get them out of their knockdown state.
Hostile NPCs are also ridiculously durable unless hit by a high-caliber gun or heavy weapon. When down, hostile NPCs can take an insane amount of damage. Even 7.62 rifle rounds pumped directly into their heads can take 4-15 direct hits to finish the job.
Juggernauts can now 1-hit any vehicle, no matter how well armored if they make contact with a side with no doors. They're not even hitting the engine, and they'll make the car burst into flame instantly, even if the car wasn't even smoking yet.
Ferals will now get stuck to a truck bed like they're trying to break a door and will hover there, eventually pulling out a survivor or instantly causing the truck to flame up for an unknown reason unless they're knocked off or killed.
Characters will ignore button presses due to the targeting system failing to select a target due to zombie congestion.
Ferals can cause a glitch that will allow them to go under a player and pop them up into the air, preventing them from attacking while the feral can freely attack. This is inescapable as the player will be popped up every time the feral moves to attack again and again, and no actions can be taken unless the feral stops attacking and allows the player to land long enough to press a button.
Quest-necessary NPCs will routinely spawn into unreachable locations.
Hopefully a hotfix is on the way to alleviate at least some of these issues.