I think the stealth element could be pretty good if done as stealth lite, ie not loads of meters and stuff showing danger etc, ie not like metal gear, wouldnt fit in with uncharteds game play. If the stealth was just hide behind walls, sneak past guards, stealth attacks (already in there) etc, i could see that working well. It could be pretty useful in areas full of bad guys just to be able to sneak past a few without having a huge gunfight if thats what you wanted to do.