Zombies aren't know for their intelligence.
What zombies? establishing the fact that they aren't real, so therefore there is non a 10/10 example, there are a lot of kinds of zombies in movies/games (There is not a Universal kind of zombie anymore), for example "Zombies World War Z" they run, In this game they also run (Normally they don't) and they are scary like sh^^ cause they easily overrun anything with speed and numbers, In Killing Floor 2 They aren't smart, not that fast neither but they are as hell as agile, and lots of them have a role they perfectly fit, that's a sweet model to copy from (I loved if the zombies from this game where as dynamic and fluid like those), In left 4 dead 2 they are stu*** as hell, but, they can surely find their path to the player (Thats something that usually doesn't happen here) Here what you usually see is: They get stucked at doors (Even when they destroy the door), they run away from stairs, ladders, they continue to hit walls even when they already breach and can go get you,etc, the IA is clunky beyond "not very smart zombies".
There is also not really a big variety of Z in this current state of game, there are different models but they mostly occupied the same role, except for 2 or 3 you can count with one's hand fingers like the cop, the spider, screamer,etc.
So resuming, I totally agree with DrunkWolf on this, I hope they focus 100% on zombie behavior, zombie role, zombie movements, zombie path finding, (Memory leaks so they can add more zombies to wandering, spawning and blood moon) etc.
Because at the end, lets be honest 90% of us is here for the Zeds, not for the construction stuff,Its a nice complement but, lets be honest, we are here for the Zombies.