And I'm also ambivilent. I have opinions, but I'm an open-minded individual--I will happily change my tune if presented with a compelling argument. I know perfectly well I've not thought of every side of this issue. I think it's pretty complicated.
I don't think there is a problem with thought-out criticism, or thought-out praise. If either one is empty-headed, it's not good. When it comes to Twilight, I think a lot of the criticism, particularly by authors, is a knee-jerk reaction to its popularity. That doesn't mean all of it is.
But whether you think Twilight is good writing or not (and to me it depends in part on how you define "good writing; on a technical level, I think the writing is merely competent; when it comes to storytelling, I think she's pretty good), when faced with a work that has the kind of broad-based success of Twilight, you can say one of at least two things:
1) Readers are mostly stupid and don't know not to like bad books; or
2) Readers are generally fairly smart, so Meyer must have done something right even if I didn't like it.
#2 makes more sense to me. Personally, Twilight wasn't my cup of tea. When the books came out, though, I was working for a big firm and it seemed like half the place was reading it. Secretaries, other administrative staff, educated professionals, men and women from around 18 years of age to 60. To me, that's empirical evidence that Meyer did something very right. The other bit of empirical evidence is that Twilight, before being published, was the focus of a bidding war between publishers who desperately wanted it. That war got Meyer a $3/4 million advance as an unknown author with no prior novels.
That doesn't mean Twilight is immune to criticisms for bad writing, but I think the level of criticism it gets, as though nothing about the book was done well, doesn't seem reasonable to me given the facts. Rather, it seems to me that given the writing is merely at a baseline level of competence, she must have done other things really right to still succeed the way she did.