Beat the story last night. They make you play it essentially 3 times, but each time they do, it gets shorter. So don't worry about having to fetch items again. And they change up the enemy placement.
It felt like a basic DLC, I guess the third DLC for the original Alan Wake would make sense. It explains a bit about what's happened since then.
I enjoyed it, but I would also say I enjoyed the previous 2 DLCs more.
Havent tried Arcade mode yet. Most of the achievements are related to this mode.