I wasn't a huge fan of the demo back when I tried it out at the Capcom holiday event - but I have to admit if you liked the co-op in Gears of War 2, you're going to want to give this a go. And I give a grudging nod to the game for allowing split-screen; I don't see that enough these days.
Just be ready to not be scared at all and to always - wait, never - shoot your buddy when they're taking on the Pyramid Head-looking guy.
Here's the official blog notice from Sony (and can someone tell me why he says "February 2 is just around the corner" when February 2 is in fact today?):