They might as well make this OVA into a hentai.
Story: Like a hentai, there's near no storyline.
Art: The art is quite bad compared to the original series, I can see quite a number of 2D drawings. But the coloring is good, for the most part.
Sound: Sound was ok, the best part of this ova imo is the ED. The OP doesn't fit in the progression in this OVA. Voice acting was ok for the most part, but the narrator at the front sounds a bit strange. I thought it would be the main male lead's (normal) voice.
Character: For the most part, they stayed true to their original character traits. But aside from that, the guys were portrayed to be more "ecchi" than normal.
Enjoyment: Well, the only part I liked was at the end , smth abt the zombie head. The rest of the ova? Might as well make a hentai =.=.
Overall: This is an ecchi ova from a horror-ecchi-etc. anime, just cancel out the horror. What to say?