Are those cute wool coats actually warm?

Are wool coats, such as this one http://media.kohls.com.edgesuite.net/is/image/kohls/271573?wid=230&hei=230&op_sharpen=1, actually warm in the brutal cold us midwesterners get? They're adorable and I've wanted one the past few years but I don't see how they can be that warm. And what about fashionable leather coats?