I love the Nook Color, its a fantastic device, I would love to get one.
But I would be using it as an ipad alternative, or an android tablet, call it whatever you like. As far as reading books and novels, I cant read them on computer screens, netbooks, or tablet pcs. I get headaches and blurry vision. Only Eink for me. Same for manga.
Nook Color is a great device, but Id use it in addition to the kindle, not in place of it