Now, to be fair to this movie, there wasn't really much to work with. They were fairly true to the terrible book; in other words, it was terrible.
I think the Director was really lazy. I think he just came to work once. I think he showed up at the beginning of filming and said "Okay, Kristin Stewart? I want you to deliver your lines completely dead pan. No facial expressions, no change in voice tone, nothing. And above all, DON'T SMILE!!! Now, give me happiness!:

Excellent! Now give me anger:

Brava! Now give me love:

You are marvelous! Now I'm going home. See you at premiere."
Actually, before he left, he was sure to tell Edward Cullen that no matter what he should look like a heroin junkie who's making eyes like he's trying to find the 3D sailboat in a hidden image.
Oh, and to make everything look blue.
But to be fair, it really was an awful book.