I liked Twilight when I went through a pathetic, angsty phase in high school. My girlfriend at the time was really into it and I thought I'd check it out. My first mistake was in thinking that I should be with her anyway. My second mistake was trying to like Twilight.
Girlfriend--whom I'll call Rachel--was "in love" with two people (me, supposedly, and somebody else). She read Twilight and apparently equated herself with Bella. Life became whiny, tear-filled, and dramatic. I waited a year and a half for Rachel to get over the other person. I was patient;I don't know how many times she cried on my shoulder. Finally I went to college and discovered what a normal relationship feels like.
I have big problems with Twilight now for a number of reasons. The biggest one though, is that it encourages girls to be passive. Bella really doesn't have a personality. I think that's what appealed to Rachel most--she saw herself in Bella because Bella is like an empty cup that any reader can fill with what they want to see.
What's worse, Rachel actually argued that Bella was a strong female character because of the "hard choices" she had to make for Edward.
Twilight, which is really big for preteens and teenagers right now, models unhealthy relationships and calls them normal. It is not OK for Edward to watch Bella while she sleeps. It is not OK for Edward to tell Bella who she should and shouldn't be friends with. Finally, I don't care how much it hurt Edward, it is not acceptable to leave someone and then just disappear. Bella's extreme reaction to Edward's absence (New Moon), however, demonstrates just how dependent she had become on him. In my opinion, Bella needs therapy and a personality transplant, and Meyer should retire from writing altogether.