The Twilight books aren't "bad", really. If you actually take the time to read them, you'll realize that Stephanie Meyer's writing skills aren't terrible. Her use of language is complex, given that it was directed to teenage girls (definitely better than say, Harry Potter), and her characterization is arguably good. Even if you don't like the plot, or the material, or whatever, the books aren't majorly flawed.
Well, MOST of the books aren't majorly flawed...
I think the reason why there is so much negativity about Twilight is because of the irritatingly, massive amount of media overexposure it's receiving, not because of the books themselves : ). C'mon guys they're only fangirls, you can fight them off if you've got a sizable gun...