The reason why I bought this game was because someone wrote a comment in a newsgroup along the lines of "Doom 3 was quite boring and not very scary, but F. E. A. R. was so scary I was only able to play it half way through before I couldn't stand it anymore". I was like "cool!" and since it was cheap in the online store, I bought it.
While technically superb, I was quite disappointed with the contents, though.
Technically the game is on par with, if not even slightly superior to Doom 3. Dynamic lighting and real-time dynamic shadows not only worked very well, but they were very well utilized (unlike in Doom 3 where they were not utilized almost at all). There were many scenes which took great advantage of the lighting engine.
While in no way a novel idea, the "bullet-time" feature was well implemented and very useful.
Avoided or at least lessened some of the most typical FPS cliches. (For example, climbing a ladder requires both hands, and the character will put the weapon away, and the weapon cannot by fired while climbing. Also nearby explosions compromise your aiming accuracy for a while.) Still had quite many of them, though.
The game was lauded for the enemy AI. While I didn't find it all that superb, it was still far better than anything else I have seen so far.
Weapon balance was very good. In the vast majority of FPS games there are weapons you basically never use (unless you are forced to) because they suck so much. In this game basically all weapons were more or less useful. Another thing is that usually in FPS games I find grenades to be much less useful than one would suppose they would be: While they inflict a lot of damage, it's very hard to use them (you seldom hit the target, you quickly run out of grenades). In this game, however, grenades were very useful and they were easy to use. Running out of them was not too big of a deal, though, which was achieved with a good balance of weapons.
The game was very linear and very, very short. It was much shorter than Half-Life 2. When I played Half-Life 2 I played like 8 hours a day, and I completed the game in something like 5 days. I played F. E. A. R something like 2-3 hours per day, and I completed it in 4 days. This must be by far the shortest "big" game I have ever played in my life. (HL2 episodes 1 and 2 can be considered exceptions because they aren't even intended to be "full" games.)
The game failed to be very addictive. While it was addictive enough for me to play it through, it still didn't manage to keep me playing all-nighters, like eg. HL2 did. Usually after about 2-3 hours I got a bit bored and stopped for that day. (Good thing, I suppose, because if I had played it as much as I played HL2, I would have finished it in a day and a half, probably.)
The most important disappointment was that the game failed completely to scare me. There was exactly one place where there was a "monster suddenly jumps out of the closet" type of scare which worked on me, but otherwise it completely failed to scare me at all. I was completely disappointed.
Don't get me wrong. It's not that I don't find this type of horror to be scary. For example, in my opinion the movie The Grudge (the US version), which is a typical J-horror movie, was quite scary. It was quite awesome. This game tried to use the same style of horror, but it completely failed to scare me. In most of the "scary" scenes I knew that "yeah, I'm supposed to be scared right now, but I just can't help it that I'm not". Even thought I wanted to be scared (because it's precisely the reason I bought the game) I just was unable to be.
The variety of enemies was completely sub-par. There were like 4 different types of soldiers (most of which looked and behaved alike), 1 type of guard, and 1 supernatural monster. That's about it. Didn't have big boss fights. (While big bosses can be considered an overused FPS cliche, they still work quite well, and not having them is a bit of a disappointment. It's like the game lacks some type of closure, some type of reward for passing a very hard obstacle.)