Oh.. Some abandoned facility you don't know the address of? Can't wait...
First of all, the plot is weak. I found it a non-immersive plot that was made even more difficult to get into with the quiet, fuzzy, vague radio calls that occasionally play. It drags on and on and on seemingly pointlessly. The plot just doesn't support the game well enough to support the 50th "The enemy has changed office locations again" and "We lost the enemy because now our tracker's broken." Basically it drags on frusteratingly. Perhaps if the game was a bit more enjoyable this could be overlooked but when you hear the typical cutsie blond daughter in the office building say "My father's in some abandoned facility I've never heard of" and the cheesey typical hollywood lines like "I'm not leaving without my father" you start to feel queezey and frusterated that -this- is the reason you're going to have to wade through 1 soldier and his 299 identical twin brothers in the next frusteratingly open-ended buildings.
Let me state some of the major gameplay annoyances that separates this first person shooter from all the other half life clones out there. Firstly, the flash light. This game is pretty much always in pitch black. Thus, you're given a torch. Sounds fair enough? Wrong. This torch will run out every 10 seconds and take 20 seconds to recharge. And in the annoyingly open-ended office buildings with enough recycled landscape to make you wonder what was wrong with the 3d designers, you don't want to be running through pitch black or you may miss the tiny, obscure grate that will take you an hour of running in circles to spot that you missed.
Another major point is the radio calls. They're so fuzzy and hard to make out that you can pretty much only make out the complimentary American "sh*t" or "f*ck" every 5 seconds in a conversation. Missing a plot's ok right? That doesn't ruin a game? No. In this game's layout it does. Even when you strain your ears and silence all the explosions to make out the conversation, your commander will make sure to give you the most vague description of what your objective is and where you're supposed to go leaving you completely in the dark on where you're supposed to go.
This game will drag on and on. There is pretty much 3 types of buildings you will go through that are recycled over and over and over. That includes the enemies too. The plot will drag on about finding one damned character for 6 missions and even at the 6th one you'll get side-tracked on something else.
The graphics and sound are about the only things I found original and good about this game (though they hog up your system, making quicksaveaholics in for a frusterating experience).
Also, don't believe the constant "OMFG THIS GAME WILL MAKE U **** UR PANTZ" reviews. At first they might make you jump a bit but predictability and repeatativeness of the "scary" parts will make you yawn after the 2nd time. The weak plot will assure you don't stay tense for long.
Overall, I found this game dragged on, was non-immersive, frusterating and boring. If you are into first person shooters I would suggest this game. If you are just looking for a good game I would not suggest it.