My reaction during the first episode: awesome so far,oh cool the teachers are zombies now and then takashi,rei and hisashi are fighting the zombies and i was loving it but then Rei's panties flashed across the screen blinding me. And that has been what the rest of the anime was like. Boobies,boobies everywhere, i mean seriously!
The art of this anime was fairly good but there are wierd characters like rei's stupid hair. The characters were good, some were absolutely useless whose only purpose is to Jiggle their watermelon boobs. Then there is Saeko whose character is just awesome but of course excessive nudity everywhere.
On pairings i have to say takashi and saeko because Rei is a terrible character that i hate.