So it was released today for the PC, I think. Anyone buy it? Any good? I had high hopes for this game.

I just finished it last night; needless to say I started playing a bit before it was "released".
It's OK. It can be scary at points, and the gameplay is a mixture of FPS and an adventure game. You have to interact with objects, collect items, push levers and so on. Overall, it's not an amazing game, but decent enough if you're in to that sort of thing. You can't save anywhere, which is a bit irritating since there are areas that I had to replay five to ten times just to reach the next save-point. There are also parts where you don't exactly know what to do next, and spend too much time just wandering around, looking for stuff to try. I had to resort to the walk-through maybe five times in total.
One innovative aspect was how the game deals with Jack's (that's you, the player) madness. If he sees scary thing, if he stands too close to an edge, if he is frightened or distrurbed his vision goes blurry and distorted, his movements become a bit disoriented and so on. If you see enough crazy ****, you can even lose your mind and commit suicide on the spot (it's happened to me). If you play it, play it with the lights off (the game even tells you this.)