Hold on, don't get all indignant about it. It's actually a decent zombie tale; once you get past the anime. Additionally, the anime isn't all the bad; the zombies are done very well. I'll let the Wiki blurb explain the plot.
"Highschool of the Dead is set in the present day, beginning as the world is struck by a deadly pandemic that turns humans into zombies, euphemistically referred to by the main characters as "Them". The story follows a group of high school students, the high school's nurse, and a young girl as they fight their way to safety through the deadly streets of Japan during a worldwide catastrophic event known as the "Outbreak". As the cast tries to survive the zombie apocalypse, they must also face the additional threats of societal collapse, in the form of dangerous fellow survivors, and the possible decay of their own moral codes."
First, while some of the animation is really good, life like and such, some of it is typical anime. Eyes are too big, as well as boobs at times. There are lots of up skirt shots, that the Japanese are so fond of. Most irritating of all is the anime habit of shifting into what I call "Hello Kitty mode", where the animation morphs momentarily into super simple, over exaggerated style; ala Hello Kitty. Hey, my daughter is the age that she was into it when she was younger; hence my knowledge.
Secondly, most anime has an under current of the repressed sexuality of Japanese culture. It's released in gratuitous scenes with nudity and sexual innuendo. I am not a prude. Still, there were times that it detracts from the story.
Lastly, and this isn't really a big one, at least for me anyway; is the action at times. Close combat can be portrayed WAY over the top; at times even putting John Woo to shame. I can get past it, others may not be able to.
In conclusion, I'd say that if you like zombies and anime, you'll like this one. If you are a zombie fanatic, give it a try; it's better than most low budget zombie flicks you've sat through. If you can't stand anime, even the zombies won't be enough to get you through it.