I would say the fact that she barely ever smiles or jokes around. I thought Bella in the book was really funny and sarcastic and none of that translated in the movie. It took itself too seriously.
I chose her facial expressions because there's the scene in the bio class where she's first talking to Edward and she makes a movement like she's about to throw up. Plus the scene where she's in the hospital bed and she starts stuttering and freaking out because Edward says he's going to leave her is really irritating IMO.

It drives me nuts... It's like she's a robot or something.

i don't like how she acts in some scenes.. she's really emotionless.. even in the trailer of New Moon when Edward leaves she's like indifferent.. instead of being dazzed, hurt in the book the feelings were so well expressed but not like that.. well i didn't even like how she talked in real life when receiving the award at MTV she was like really weird and please don't blame it's just my opinion.. like everybody she has her pros and cons :)

IMO She needs to act more feelings she looks the same a lot! Hopfully New Moon proves me wrong!!! :P

I like her (:
I think everyone's forgetting that Bella didn't let it sink in until she went to her room and collapsed on the floor, she was dazed and numb, that's why she doesn't look that upset. For example: 'I was surprised by how calm and reasonable my voice sounded. It must be because I was so numb.'

well i'm kinda irritated with everything.. i so totally agree with shelby when it comes to kristen's acting..she has weird ticks that she makes and it's really bugging me.. and she can't close her mouth for god's sake.. but still even though i'm not a big fan of kristen i can't imagine anyone else being bella.. i think that others would be even worse... i'm just sorry that stephanie didn't said anything cause she was on the set of twilight and new moon...

what r u talking about. i think that she's perfect. i like how kris plays bella.

Yeah, me too...I don't know, she seems kinda weird and awkward, but that's who she is and I'm really glad she isn't like that stupid Paris Hilton who is just trying so hard to get attention, but in fact she can't even do a normal posture...She just says what she thinks and maybe, yeah, I don't like everything what she does or not but she has her own opinion about certain stuff, which some "stars" don't really seem to notice....So I really don't care about her mouth nor her nose and especially not about her acting because she knows what she's doing...

Well i like er shes amazing!

i hate this part of kristen. can't she just close it?

She's GREAT as Bella! What are U talking about?!

But still love her as Bella!

i think she is a great bella

I Like her as bella!

i love kristen!! she is the perfect bella! :)

The awkwardness bothers me sometimes, but I guess that's just the way she is.

She is weird, but I think she's perfect for the role. When I watched the movie I really loved her :)

They made her look exactly like the book described her in the movie, but her acting sucked... she had the same expression the whole time, it was like she wasn`t even trying :(

She just look's totally awkward, but she look's a little better in New Moon.

I didn't mind her in other movies like Speak and Into the Wild, but I just don't think she fits the part of Bella.
I was disappointed with the New Moon trailer because everything she says is monotone. "Kiss me." "I love you" etc. And I agree with Adriancik92 about the part in the trailer when Edward leaves. I remember it being so sad in the book and yet there was no emotion there in the trailer. Although I think I blame that more on the music than on her.
I still think they should have found a more relatable Bella though. I get so distracted by her twitches and stutters that I can't focus on the story. And seriously, crack a smile.

Bella is so Happy wit Edward and Kristen doesnt show it. she's monotone

Really pissed off about her...
IMO she ruined the movie.

i love her:D

She is my idol!