Just to clarify: 24 hours to redeem from the time of its release (should end around 1-2 PM ET on Friday), and you must own the base game already.
I spent a little time with it this afternoon. There's two big additions that this DLC brings to the story mode: There's a new chapter called Arctic Cruise, and a new challenge mode called Death Wish. Here's the major issue: You need to progress through Death Wish in order to unlock chapters in Arctic Cruise, and Death Wish is really

ing hard. I enjoy a challenging 3D platformer but this is overdoing it to the point of being completely unenjoyable. It seems to have been created solely for the the speedrunning crowd that has mastered the game and knows the layout of these levels like the back of their hand.
There is an EZ mode available for each challenge, but to unlock it, you need to spend five balls of yarn. Yarn is a limited resource in the game used to create hats; once it's gone, it's gone. If you want extra you have to grind community-made levels and play through those to find more.
If Death Wish was an entirely optional challenge mode for people who wanted to simulate getting kicked in the balls over and over, then sure, sounds great, let those people enjoy it. But to gate the legitimately good content behind it is mind-boggling. I lost all desire to continue with this DLC, which is a shame because the base game is remarkably good and Arctic Cruise looks like a worthy addition. But Death Wish is straight garbage and ruins the whole thing.
EDIT: Good news: Devs came to their senses and took down the Death Wish requirements to play through Arctic Cruise. Bad news: Arctic Cruise actually kinda sucks. Confusing layout and awful camera thanks to some of the tighter corridors (especially in Act 3). The cruise ship is super detailed but never used to its potential. Not a very good DLC at all.