Gotta say it's one of the most scariest games I've ever played, really creepy and slow paced, especially those tree monsters gave me shivers down my spine everytime I met them.
Anyway, managed to play it with a walkthrough, to make it more fast, and it was pretty entertaining, I don't understand the bad reviews, also - I got the bad ending, though I wasn't very bad.
The game doesn't give you clues of what it is good to do or don't do, maybe for replayability reasons, but I watched all the endings (and the secret ones) on Youtube.
You have to play it if you are fan of the genre, I haven't watched the movie yet, I don't know if they are related..