I'm a little baffled at the reviews of two big magazines in my country. While i was sure it would be a safe 80%, one of them even gave it only 69%.
The Alien would be too unfair, bullets can't hurt it and so on. I don't know, maybe it's because i'm a fan, only played it on medium or they just suck at stealth games, but my frustration always stayed at minimum.
Also there were complaints about androids noticing you, though they turned their backs on you. Never happened to me. Either their test version was flawed yet, or they didn't even notice that they have to sneak - and not to walk.
Oh well...
edit:
Oh, the other one turned it from 73% to 80% now.
The reviewer admitted that he took a wrong approach on the game, after listening to reader comments and his workmates.
I kinda thought as much. Good for him that he noticed it's not CoD and it's suddenly more fun lol