Alright, here is an honest to goodness review. I know there are quite a few in this post, (Quite good ones in fact) but i'll add my two cents. And for the record, I don't read reviews anymore,Too many bad reviewers, too many skewed points ETC ETC, Yadda Yadda. My platform for this is Playstation 3.
The game is dated. I'll say that right out of the gate. It reminds me of Duke Nukem Forever in this way. The graphics are not sharp, the animations need work, the weapons need a bit of re-balance (Assault Rifle recoil anyone? Even with the stock upgrade?). The A.I Is problematic at times, with marines not even reacting to nearby aliens, or the aliens themselves charging in and disregarding stealth as was stated earlier. But to be honest, that doesn't much make a difference in just how fun this game is.
If you like the films, as I do having grown up with them, you will appreciate all the scenery and the way it's changed since the events of Aliens. Dark corridors, the sound of air vents above you moving with unseen weight, and the ever ominous clicking of your motion tracker. Good stuff. And the Aliens, yes they charge you, hit and run tactics, but trying to spray an alien in napalm while it hops from hallway wall to hallway wall, while worrying about the ones behind you and the reason why your armor is steaming and hissing makes for tense fun. XP earned in game through challenges, which unlock weapon camos and such, also counts in the most refreshing feature of this game, the multiplayer.
All bugs aside, the multiplayer is a blast to play, stalking players as an alien spitter, sniping them from afar, or shooting that one firebomb that will save the squad and allow an escape. Everything is here, from Team Deathmatch to Escape (A Left 4 Dead feeling mode) are present. The only problem i've encountered so far is some mic problems, as in the audio chopping up via latency issues. But overall, this is not CoD or Battlefield, but a refreshing change of pace.
I hope this helps some out there to decide on the game, it's not perfect, but it's a great ride.