I'm playing it at the moment and really enjoying it. Went with hard mode to begin with, and it really leaves you no room for mistakes where the Alien is concerned.
They've captured the feel of the movie perfectly, from the level design and artsyle to the sound design and little references to the movie.
I like how underpowered you feel. I've found a revolver so far, but it's useless against the Alien and takes like six headshots to down an android. Haven't had the chance to use it on a person as the Alien gets to them first.
The Alien feels very smart and will often leave a room only to double back and try and catch you, wait for you in vents if you try and use them to evade someone else and wait outside rooms and hiding places if it suspects your in the area. It also uses the vents to move around the levels much quicker than you can.
I've heard it drags on a bit, but I'm fine with that, I'm planning on playing it in chunks anyway. Reviewers complaining about the Alien being too random and good at spotting you as well as the save system need to get good, I like that it doesn't baby you.