It shouldn't come as a surprise that Yoshiaki Kawajiri helped write the script of Bio Hunter. The characters, the monsters, even the lore is very reminiscent of Kawajiri's films. But directors matter more than writers, which is why Bio Hunter is still a minor disappointment, regardless its potential.
Even though the film is only 60 minutes long, it tends to drag a little. There's too much dialogue, not enough horror, not enough action. This may very well be a budgetary problem, but that doesn't make it more entertaining to watch. No doubt Sato could've cut another 15 minutes for a better overall result.
The animation quality is also relatively low, but at least the monster designs are fun and the few horror/action scenes that are present do manage to deliver. Bio Hunter isn't the greatest anime, but for people craving a late 80s/early 90s anime horror fix, it's not the worst option out there either.