The illustrated guide is my favorite (the one that SM wrote, though the others are good too) but SM gave detailed accounts to each pack member which I loved.
Certain friendships among the pack weren't shown that well in the film compared to the books/illustrated guide. Like with the illustrated guide, it's Jared and Sam who are best friends but the movie makes it out like it's Sam and Paul that are tight. Jared was Sam's second but the movie made it seem again like it was Paul.