Look, this is definitely not a groundbreaking zombie movie. If that's what you're looking for, you're missing the point. What some of the harsh reviews seem to ignore are all of the references to other horror films (Night of the Living Dead, Dawn of the Dead, 28 Days Later, Resident Evil, to name a few- I even saw a scene that was taken from Wrong Turn). This is clearly a director who knows and respects the horror genre. As an avid horror fan, I truly appreciate it when directors pay homage to others that have come before them.
Are there plot holes? Yes, and the same can be said for pretty much all films. Is the script lacking in some places? Maybe, but it didn't detract from overall impact of the film...and I don't tend to watch action/horror for the non-stop, clever repartee. Was it an original take on the zombie theme? No. But at least this movie doesn't insist upon itself like so many of the hackneyed, pretentious features that are littering the mainstream movie industry.
In conclusion, Block Z is an entertaining film that I would watch again.