It's an action game more in the style of DMC. The other heroes with you serve the main purpose of transforming into weapons (giant fists, gun, swords, etc.). They can be used in other ways, too, such as having them jump on to enemies to momentarily stun them and do extra damage. They've said you can use them in a variety of other ways, but we won't know for sure until the game is out.
Here's the blog for Platinum, where they've been detailing the mechanics more in depth:
That's the latest one, but you can go back and check out the others.
"When you see a John Woo film, it's comforting to know how shallow the world really is. The full force of the manly coolness factor with a peice of nose hair sticking out from the tiny crack between manly and cool, exposes the thinness of the male hormone factor. It takes an idiot to do cool things. That's why it's cool."
Originally Posted by Hideki Kamiya
Is that IGN thing your god or something?