It's nicely atmospheric, but the game has a few fundamental flaws.
1) The combat is kind of meh, which is okay when there's not a whole lot coming at you, but the stand-offs late in the game are kind of boring, even if they're fairly tough.
2) The story is pretty good, but the endless narration really undercuts the drama. It would be much more effective if they cut 75% of the voice over.
3) The endless forest levels gets really old by the end of the game. The two DLCs are nicely surreal and I wish that had been the end of the regular game.
4) Speaking of DLCs, the main game feels a bit incomplete without them.
5) For a non-horror writer, Alan Wake seems rather obsessed with Stephen King... yeah, the endless King quotes about horror fiction never rise above gratuitous and they're so numerous you could probably play a drinking game with them.
But there's something about the game. The story & characters are interesting and the forest scenes are genuinely spooky (even if the game seems determined to telegraph every potential scare). Worth checking out if you catch it cheap. Good number of people really enjoy it, but it's sort of like Heavy Rain in that it's hovering around something which could be really good and effective, without quite getting it right.