Oh yes, the second reason I love Twilight? It's entirely selfish. These books are just plain fun to read! As I mentioned earlier, the characters are so well done, that you really do find yourself caring about them. I am also a sucker(har!) for a first person narrative story with excellent voice. Bella and Edward are the perfect star-crossed lovers, but they manage to be interesting long past the point of standard teen romance. Meyers also manages to confront some very serious themes, such as divorce, family connections, suicide and depression, and teenage alienation, all through the lens of this very unsual relationship.
In the end, I would recommend the first book in this series to nearly everyone (okay, to be fair, to nearly all women and older girls). For the adult reader, it takes just a couple days to finish the novel, and it is such a fun ride that you won't have time to worry about whether it represents highbrow or low. If you are still concered about looking silly being seen with the now famous cover, grab this for a plane ride, and tell everyone around you that your niece is making you read it.