I actually saw it about a week ago. Fine film. Tons of atmosphere. I don't want to say too much, as it's best to know as little as possible about the plot beforehand. It's great to watch everything unfold.
I've seen 3 of the AD4 films so far, and results were kinda mixed. Zombies of Mass Destruction was pretty decent. Didn't really like Kill Theory. It felt very standard and formulaic. Didn't bring anything new/different to the table. Lake Mungo was the best I've seen so far. It starts very good, but loses steam about halfway through.