Glitch.
Like a previous reviewer, I've encountered a completely game breaking glitch.
I've done everything possible. Minus a few of the more tedious and arbitrary achievements. I've found every note and log, done every objective, used every weapon to it's fullest extent, and gotten every reaction (Including advanced) for every food and item and got the zombie to deny human flesh as a food source, yet still I get no ending. And if the ending really is just my researcher giving up hope and researching everything in an infinite loop, than that's an awful ending.
Fix the bug or the ending, but neither one is deserving of a perfect score.
Aside from that, the game was bearable but incredibly tedious. Making us get every normal reaction from every item would've been acceptable had their not been so many of them spread so far apart. That made the game feel dragged out and more of a chore than an activity.
Other than that, good atmosphere and the animation quality was pretty satisfying.
One minor change though, if you just killed a zombie, don't have it still there, ready and waiting for you to pick it out of the selection line-up.