Not going to be quite the system seller you thought it would be then... who knew
It'll still sell systems regardless mate.
As ancelotti has said, Edge has given it a 7 (which is the equivalent of 85+ compared to other sites) and Eurogamer have given it a 9.
I think the reviewers that have given it 4 or 5 were expecting a traditional FPS with zombies and have been running and gunning rather than playing it the way it should be played - as a slow-paced survival horror game where you need to take your time and think what you're doing, conserving ammo and being stealthy.
If you run around like it's CoD Zombies or Left 4 Dead blasting everything in sight then you're going to be left with bugger all ammo and will be left with nothing but a cricket bat swipe or 5 between life and death. This is a game you need to take your time with, making sure you explore areas properly to find hidden ammo and weapons...and even then, you're still going to die. A lot.
If you rush through the game you're also not going to appreciate the feeling of loss that you'll get from using a survivor for a couple of hours. Some of the reviews have said you'll both love it and hate it lol.
A true survival horror game with Souls'/roguelike features is full of instant win for me, but it appears (despite Ubisoft billing it as an old school survival horror game that's going to be unforgiving) that some reviewers haven't grasped the concept and haven't reviewed it accordingly.