They are apparently plain page journals, but each interspersed on some of the pages with quotes from the equivilent book (eg the twilight notebook has twilight quotes, new moon new moon quotes and so on) - at least according to the us sites that are selling them!
I have these notebooks, they are A5 (I think) and have plain pages. Yet some of the pages have watermarked designs and quotes from the corresponding books. You get all four of the books as well so you can do more writing, they can then be stored in the tin. I love the Twilight series and the notebooks are very pretty, and a nice thing to have if you are a fan of the books too.
So i bought them from HMV during the summer, you get all 4 in a tin, they are a5 size, the twilight one has stephenie meyers favourite quotes from twilight in it, the new moon was has her favourites from new and so on, they are plain paged and have no lines, but i absoloutely love them and for this price you should definitely get them!!