The gameplay can be a little monotonous, but I don't think it's any worse than a lot of games. Or, to put it another way, it didn't get to the point where I was bored with it. I think using light sources as your main means of attack is a pretty cool idea. On the easiest difficulty setting you can pretty much kill anything, but on any other difficulty you're expected to preserve your ammo and actually run from some enemies rather than fighting everything. The atmosphere is great; the mood is set just right and it really draws you in.. As far as story, I think it's really good. If you like Stephen King at all, then you'll probably enjoy it. The writer also cited Lost as an inspiration, and you can definitely pick up on that.
My only complaint, being that I have it on 360, is that you have to buy the two DLCs to get the full story and ending. Kind of lame.