I got my copy of The Others: 7 Sins this week and I purchased the art book with it and am glad that I did. It is not only chock full of excellent artwork but it is presented as pictures interwoven into a multitude of background stories about the characters, beasts and conflicts. It's a pity this is not listed as an expansion (admittedly there is no gameplay value there) but it adds so much to the game in describing the in-depth background.
What is your opinion? Should 'art books' such as these be considered a game accessory or expansion? What if it included one or two scenarios as an afterthought?