To be quite honest I don't think Kirsten did a great job at all, her acting was stiff and her voice (I know she can't help it) was a bit to hard. She is nothing like the Bella I imagined.
Not only that I don't find Rob attractive; so Edward was a major let down for me. But thats okay seeing as his not my favourite character.
All in all I think the normal people of Forks did a fantastic job, they acted like real teenagers
Ashley was perfect; exactly how I pictured her, even though her part was small she captured Alice perfectly,
and Emmet (Can't remember the actors name sorry) was great! again he looked like how I pictured him; he was even funny and had that immaturity that we all love about him.
Carlisle was again prefect, he just grabs your attention, I think he kind of looked like Ken (the doll), and his make-up was a bit too much at fist but all in all he was fabulous.
Esme was portrayed great as well, another one exactly as I pictured. Very motherly straight away.
Jasper, not exactly how I pictured him, but absolutely perfect, maybe the face was put on just that little to much; but then again he is usually in constant pain. I think Jackson did a fantastic job with Jasper - the hair was pretty good, it looked best when it sorta hung down in his face.
Now Rosalie is the only one I had a problem with - I thought she was suppose to be beautiful, don't get me wrong shes pretty, but really she's suppose to make everyone jealous, her acting was so-so, it could have been a bit more ... not aggressive ... but nasty/malicious. I don't know I just think they could have got a better actor for Rosalie.
I think the Cullens all deserve more lines, as most of them hardly got any at all.