This game is excellent. I love survival horror and I love stealth and it puts them together. It's genuinely frightening in a lot of places, and the sight-jack mechanic works really well. It makes the stealth aspect original while adding to the terror, for example when you get spotted and you can see yourself as the shibito runs toward you, but on your half of the screen you can't see them in the dark.
I also like the sense of desperation, picking up all kinds of objects (there are 50 weapons in total) and madly hitting the shibito with them if you get seen, which is always really satisfying.
It's also packed full of secrets so there's loads of replay value, and it took me 19 hours to complete on the first run-through. The story is crazy, you have to get a lot of the secrets to start to understand it, but I liked that.
Frankly when you consider the price of the game its easily one of the top two or three games on the PS3. I enjoyed it so much I bought Forbidden Siren 2 for PS2 instead of getting Soul Calibur 4 as I had planned to do.