The meta-aspect of it gets still more interesting in the last two books, where not only the heroes get into the book-within-a-book, but also the author of said book - who tries to influence the story and write it onwards while sitting in it, not always equally successfully. And then there's Orpheus, a rather tragic character who loves the book so much that he's willing to go to great lengths to get inside it - and then starts to manipulate it for his own purposes as well.

Was the film really very dreadful? The reviews are fairly harsh, and considering how good the cast is, that almost has to mean a dreadful script/director... though in fairness, the first book is not the easiest to turn into a good movie. The second and last ones are more Hollywoodian.