Being a big fan of something inevitably implies that trouble are going to arise when one will see flaws in the creation he admires. In this case however there are no trouble, just the clarity of the fact. Shivering Isles an expansion for Oblivion is easily more captivating than the whole of the main campaign. As for the duality of the world I think it is a brilliant idea which grew to be more than just that. Overall money well spent.