Well, I've thought about this a lot, as many critics seem totally puzzled by its allure. Let's compare and contrast to a traditional romance novel, shall we? :)
In a traditional romance novel, the girl is weak, either she's a total dizzbang and makes horrible decisions that lead to bad consequences that the guy has to rescue her from. Or she's portrayed as stubborn and stupid...so that the above STILL happens.
Meanwhile, in every spare moment, the guy, no matter how hot and smoldering, is constantly trying to get down the lead female's pants and she is constantly resisting (but unsure why).
Additionally, said female lead is usually described from among the following pool of adjectives:
blah blah blah
(just checkin to see if you were paying attention!)
likes small animals
likes to sing
a good sweeper perhaps
And while we, as female readers, do our best to relate to the lead female character, sometimes we do get swept away despite the flaws in the story; sometimes our interest is held because we're so disgusted with her and we read on, hoping she'll fall off a cliff or meet some other similarly messy end and put us out of our misery. This way we don't have to "listen" to her whine or groan in despair at her stupidity. And yet, this ding-dong is expected to ensure they either have no sex or safe sex. It's never up to the men. They have "unbridled lust," you know.
In Twilight, for once, we find a girl that goes against the grain with Bella: someone who is flawed and is not the stereotypical male's dream of a female. Bella is smart, mature, clutzy, a good student, honest, thoughtful and empathetic. Did I mention she was a brunette? :) She is also a little on the lusty hormonal teenager side, unlike her male lead....Edward.
Edward Edward Edward....where do I start?
He is a gentleman. He shows restraint people! (and by "people" I really mean men!) and do you know why restraint is sexy? Because the men of this age are NOT encouraged to use it! Between all the objectifying of women (get ready, I'm gearin' up here...) and all the media we are exposed to on a daily (nay, hourly) basis men now have the attention span of a gnat. They are encouraged to get what they want and get it now. So women are encouraged to skip the niceties and show up lookin' smokin' hot (I think that's what the kids are callin' it these days). Even the men who seem like nice guys have an expectation of some ...ehem...payment. Most will deny it, but if they pay for dinner and pick her up and drop her off, show her a nice time, he expects at least a kiss at the end of the first date. (admit it!! at least a kiss!!)
Edward, on the other hand, watched Bella sleep for weeks, protecting her, saving her life for God's sake, and still he didn't kiss her!! That, my friends, shows monumental restraint, which implies maturity. Which is hard to find in guys. (sorry guys!).
It doesn't hurt that Edward is smokin' hot.
Excuse me while I go swoon....