If you like Ico this game is a must-play. It reminded me of a version of Ico incorporating elements from folk tales like Jack & the beanstalk except, instead of dragging Yorda around the whole game you get to control both lead characters. There are also no block pushing puzzles or battles with shadow monsters but overall it felt more like Ico than anything else I played this gen. There are a couple of boss fights, but they're more like active puzzles than combat and there's a section where you ward off some wolves but it's pretty basic.
It's pretty short, I got a copy last night at at about 7PM and was done with it before midnight, but don't let the length bother you. It looks incredible and, especially in the mountain section with the tower (I think it's chapter 3) there is some really interesting platforming stuff that could only be done in this two-character control scheme.
There are also a few darker elements as the game progresses. At one point, I saved a guy from hanging himself after his house burned down and at another, I had to make my way through a battlefield filled with the blood and corpses of giant soldiers. (not really big spoilers, but marking them just in case)
I'm already a big fan of Starbreeze's games, but this was a very different experience than the kind of thing they did with Darkness & Riddick.