*WARNING CONTAINS SPOILERS*
The game looked very promising in Gearbox's demonstration of the game shown in 2011 but that is not even in this game. The games ultimate downfall came from the many different studios that took part in making this game, although it has been in production for six years the game is rushed as the other studios destroyed it so Gearbox had to do last minute changes to the game.
The biggest problem is the bone idle A.I. The Aliens are not scary at all, you can run past them in most missions without them giving a care in the world, your A.I team mates do nothing to help you in fact they more often than not hinder your progress through a mission and the fact that you are fighting Weyland Yutani private military through most of it is annoying and disappointing.
On a brighter note the sounds are nailed perfectly, they really immerse you in the game, the environments and lighting are top notch. Without a doubt the best mission is Raven (You'll have to play the game to find out why).
And so we come to the reason i give this game four stars, the multiplayer. the multiplayer saves this game in my opinion, it is fun, scary and tense and with no A.I to get in your way it makes the game enjoyable, game modes like Escape and Survival are what makes and Aliens game, Marines having to hold up, weld doors, place turrets to survive facing endless swarms of player controlled Aliens, it's good bug killing fun, with friends the multiplayer is very enjoyable and every game is different. The teams are balanced really well and you really have to rely on your motion tracker to survive. You know the saying lone wolves die young? well yep that's exactly what happens.
I would recommend this game just for the multiplayer, but definitely get the game for PC if you can run it because the console versions are dramatically worse in terms of visuals and crashes, screen tears etc.