I'm several hours into the Marine campaign now. If you're not thinking "Game over man, game over" the entire time, then you're either not playing the game right or you havent seen Aliens
They've really captured the "Anything that can go wrong will go wrong" feeling that was all over the movies. I dont care what the reviews say, the game feels right. To me that really helps it.
Also, the control issues every review complains about, are absent in the PC version. Unless they're talking about aliens crawling on walls. Thats not a control issue exactly, just a disorientation issue since we're not exactly used to thinking that way