Just experienced the changes today, the zombies don't have Superman's sight anymore so stealth is back, although maybe a bit TOO implemented as I sprinted right past some zombies and they didn't even notice, plus their sounds are gone so they can sneak on you rather easily, also their attacks are faster, though weaker and their health has boosted so their's no more one shots with the axes.
Also the zombies can get tired now which is odd when every zombie movie/TV show in history has taught you that zombies don't get tired.
Though these servers suck now, I spent hours building up 2 good camps, one with 3 trucks and 3 tents and one with 3 of the smaller tents with some gardens filled with awesome loot, but the servers restarted and when I came back online all my stuff was gone, all that hard work gone, it really pi$$ed me off.
I just hope they fix that soon or at least add in some tent crafting so I can prepare.