The Depths of Meta: How far are we meant to go?

While watching Stranger Than Fiction, it is nearly impossible to miss the "meta" aspects of the film.  The very concept draws attention to the notion of story-telling, the same story-telling that we are enjoying as the film progresses.  The thing that I found interesting about this is the fact that the story0telling that the meta aspects of the film highlight are those that would be most effective in the original book.  There is little to no attention pulled to the fact that the viewer is, indeed, watching a movie.  This begs the question of how far one is meant to look into the meta aspects of adapted film.  The original book is a "book about a book," but the film is a "film based on a book about a book."  Is the meaning deepened by this additional layer, or does the film simply fit the role of telling the audience the story provided in the original text?  I have trouble deciding how far I am meant to go when it comes to dealing with multilayered meta-film/text...  what do you all think?  Does the fact that the book was made into a film add additional meaning or is it simply for the enjoyment of the masses?