Well, there's the love story between Edward and Bella, which is incredible. I also love how conflicted these characters are and how at the beginning of the Saga neither really knows themselves. I also love the way they explore the family bonds both between the Cullens and between Bella and Charlie. It's not only inciteful, but extremely moving. I also love how each of the Cullen's have found their own reason for choosing the vegetarian lifestyle. It wouldn't have been nearly as good if it had been Carlisle enforcing his will on the others. Plus vampires are just soo cool! And I like the fact that Stephanie Meyer put her own spin on the Vampire lore. Also I have to mention, even though I was already completely obsessed before the movie came out, two little words: Robert Pattinson. Nuff Said.