Notable is the emotional approach, where building tension of character survival and killing zombies comes second to the feelings main characters harbour for the zombified. Story is, frankly speaking, rather standard issue, but it is worth a glimpse for it's atypical main cast and problem approach.
this anime does NOT have:
-shallow characters. They may not have a full psychoanalysis conducted, since, you know, ZOMBIE APOCALYPSE takes place, maybe? Calling them shallow is just stupid.
-actual gore
-zombie shots. as in, they're censored when they don't need to be shown. It is not bothersome though, just picture a moaning, shambling corpse clad in aura of darkness.
-much fighting scenes
-obnoxious fanservice. the only instance i recall is when they wear swimsuits for cleaning water tank and when they bathe the dog in underwear.
So, this is not a story about zombie apocalypse with HS girls in it, but rather about HS girls coping with zombie apocalypse.
