This is the first single player game that I've blasted through since Super Mario Galaxy 2 earlier on in the year. The atmosphere in Alan Wake is thick, the story is well-paced and takes you to some truly great set-pieces/environments. I love that it rewards that player that seeks out every nook and cranny with additional story elements.
Some additional thoughts...with some spoilers ahead.
Alan Wake certainly strikes me as semi-autobiographical from Remedy. Alan Wake kills off the main character in his critically acclaimed New York noir revenge tale, (or, alternatively, hands him off to Rockstar) and loses the ability to write. There are elements there but the actual craft is weighing on him too much. Alan Wake's storied history is 5 years old, a supposedly open-world horror game that would revolutionize the genre. Instead, we have a great linear narrative that cherry picks from all the greats (both story-wise with King references, echoes of Silent Hill, Twin Peaks, X-Files, and the Twilight Zone, and gameplay wise with RE4, Silent Hill, and Half Life 2 comparisons). It may not be as fine tuned as some had hoped, but I can't wait for the next "season," plot holes and all.
Playing on Normal difficulty proved way too easy, although some of the weird checkpoints could definitely frustrate much more if the game was harder.
Ultimately, I loved this game, and I see it as a great companion piece to Silent Hill: Shattered Memories, a game that was, ironically, made in a very brief amount of time development-wise, yet touched on a lot of similar gameplay mechanics and narrative structure.