This comment is partially extremely lame.
Do I need to tell you? I'm still shaking. This game IS scary. Very. Perhaps a little too scary for many players. It's much scarier than Penumba (says the man who used to consider Penumbra the scariest game ever). It's not much of a surprise, though. There's so much talent and genius back at Frictional, and witch such advantage it's no challenge to make such a masterpiece, which Amnesia undoubtedly is.
The first half of the game is *relatively* calm, and more than anything serves to getting to the main hero's skin and getting to know the castle, which's internals the player will wander around. Of course I don't mean to say there's not much happening in the first half, on the contrary - the game gives you a good scare during the first 15 minutes of it and trust me when I say, this game's level of horror has a rising tendency. The deathly danger also doesn't linger at all (and this particular situation will be very familiar if you at least blessed yourself with the demo version of the game). Since the very beginning of the game, you also keep stumbling upon various shards of the story of all kinds - be it the notes or pieces of the main hero's diary scattered all around the castle, or the ever so frequent flashbacks, which are torn apart in such a way it only confuses you more and more.
It's the second half of the game when the real meat appears on your plate, though. A literally heart attack ride. In an instant, without any warning, you open a completely ordinary doors, and from the near pitch blackness a monster crawls out in your direction. One would think of running away, but this monster happens to be just about three times faster than the main hero, so there's very little chance of escaping. The only realistic solution is to hide. Sadly, that's almost always too easy, and not only for that the game's overall difficulty is rather low. Do you find yourself in a situation when you need to get through a room with a wandering monster, but it gets you and bites you butt every time you try to run for the gate? Have no fear, simply let it kill you three to four times and they kindly kick the monster out of the room. I kid you not, this is really happening here. However, even though it sure decreases the tension level, it's still damn high, and then it's a pretty interesting way of helping a player in need. The local riddles and puzzles are all pretty much logical and unless you lack some common sense and basic brain functions, you shouldn't find any difficulties with either of them. The only serious critique I can throw on the game is for its story and imprimis the ending. The story itself is unfortunately quite flat and uninteresting, and it's basically a masked cliché about ugly rituals and torturing. Despite the slow pace of its unravelling, you start to get a pretty accurate picture of where it's all heading to about quarter way through the game. And yeah, there's not much to look forward to. Pity. As for the ending, there are three possible, and they all suck (and the differences among them are purely cosmetical).
The game is also pretty short. Give or take 6 hours and goodbye. I usually expect 15+ hours with adventure games of such nature, but too bad. Lucky enough there's the developers commentary included in the game, which is a total must-hear (if you had even the slightest doubts of the genius minds at Frictional, teh commentary will show it to you). If you'd be playing the game for the first time AND had the commentaries on at the same time...well let me just recommend leaving those commentaries for a second playthrough.
As long as you don't consider Left 4 Dead to be the top of what the horror genre has to offer, and you don't demand at least one gun to each and every monster in the room to shoot their heads off, Amnesia is definitely worth giving a shot. If you love adventure games, the horror genre, and coincidentally also happen to be a fan of the Penumbra trilogy, then Amnesia is a **** must.
+ The sound design, it's scary as hell, the graphics are very nice for an indie budget title, an absolute logic of all the riddles in the game, an absolute lack of bugs and other pranks, an almost perfectly polished engine, an extraordinary sophistication
- The self-decreasing difficulty in case of frequent dying (feel free to consider it a plus if you like the sound of it), the story, all three endings, short game time, the voice acting (although, for an indie budget title it's not that bad)