SPOILER WARNING!
The more I think about Bella, the more I find that there is more to her than meets the eye.
Starting with her looks: she sees herself as rather plain and 'klutzy', but as Edward says, she doesn't see herself clearly. Even though I was spoilt by the pictures of Kristen Stewart (who plays her in the Twilight movie, http://www.twilightthemovie.com/), I didn't imagine her like that (and still don't). I think Kristen is prettier, though she captures the unusualness quite well. Anyway, what Stephanie Meyer says about Bella's appearance on her site draws my attention:
I have decided to tell you what she looks like to me. But I want to stress, Bella's looks are open to interpretation. ( http://www.stepheniemeyer.com/twilight_faq.html#bella)
Shall I take this to mean that it's the reader and not the author who interprets the text and that the author has almost no say in how their own creation is interpreted? I like that, but not to the extreme: every reader has his/her own view, but the author can always say what their intention was and how they pictured the character, the plot, etc.
Anyway, back to Bella. I side with Edward on the point that she's not as ordinary as she thinks. And she's been through a lot. She had to learn to take care of herself early on, because her parents got divorced and she had to look after herself and her carefree mother. And she didn't seem to complain, not even through her teenage years, when everyone complains a lot about everything. When she moved to her father, she again was quite capable of taking care of both.
What is quite striking is that she is not afraid of vampires. What's more, she wants to be one of them, even though she is told that it's extrememly painful, even though she sees that it's very difficult to get the better of the thirst for human blood, etc. And she seems extraordinally detached from humans: she is quite capable of forming relationships with vampires (and werewolves later on), but not people. Vampires and werewolves are mortal enemies (or should I say immortal?) and yet she is friends with both. But that's not all. The fact that Edward's talent to read thoughts, Aro's talent to read minds, Jane's talent to torture do not work on her make me think that she is not ordinary at all and that she has some talent, which will surface when she becomes a vampire. I think she will, because it looks like Aro's guard will track her down eventually if she doesn't. (I'm getting to the end of New Moon).
In Twilight, she is ready to let James kill her to save her mother (and arguably Edward) and in New Moon she is ready to save Edward, even though there's a slim chance of success and a strong likelihood of being killed. Her sacrifice reminds me of Harry's in Deathly Hallows in a way. Only when they surrender to the thought that this is what they should do and that's the end of it, does the sacrifice really work. Harry saves the day, while Bella has to be saved by the Cullens. Still, she manages to escape from Alice and Jasper's watchful eyes and she really accpes the fact that James will kill her.
I didn't expect the Cullens to leave her. But I am still more amazed that she manages to get out of the severe depression she sinks after that. True, with a lot of help from Jacob, but it takes quite some strength of character and recklessness, as it turns out.
So, these are my first jumbled thoughts on Bella. I'm sure there will be more of them as I read on.