Honestly? I hate it because of the two main characters, Edward and Bella.
I like to have something in common with my main characters, so I can relate to the story better and really get into it, and Bella is unrelatable and unrealistic. For a seventeen year old girl, she doesn't do anything normal girls would do and acts way too old for her age. Teenage girls make mistakes and have mood swings, neither of which Bella does.
She paints a very anti-feminist picture and when she goes into a living coma when Edward leaves, it's disappointing that she can't live on her own without him. People who have had their one true loves actually DIE or also leave them can survive fine, but apparenly, she can't.
Edward scares me. It's not romantic when someone watches another person in their sleep. He controls a lot of Bella's decisions, such as he'll only turn her into a vampire if she marries him. I hear very little of his personality and see even less- his only standout traits are picking at her for her danger magnet-ness, how he constantly tells her he's dangerous (it's her right to take the risk, though), and his looks, which seem to be the only thing Bella's concerned with.
The other characters are a mix of stereotypical and thin, and when Renesmee came along, I couldn't stand her. I know she was a half-vampire, but the little girl was way too perfect. I recall the perfect term from my fanfiction days of what she is: Super Mary Sue. Just could not stand her.
A former Twilight fan who thought about things a little bit.