Naughty Dog has said that Uncharted 2 will consist of about 40 percent puzzle-solving elements and 60 percent action.
However, that being said, the developers want you to focus more on the pacing, exploration, and action as the puzzles solving will be more subtle and seamlessly integrated.
"I think gamers are going to notice that it's going to be a little more action packed," Naught Dog's Arne Myer told Kotaku. "There's a little more tension, a little more action behind everything [Drake] does.
As far as cop-op goes, there will be none of that.
"We thought about whether we could have cooperative in the game," Meyer said. "But the game is really centered around Nathan and his personality. It didn't really make sense to do coop."
More through the link.