I am pretty Switzerland on most things, and this can be one of them.
I do find Bella whiny and annoying. But I also find her to be a strong-willed, determined, intelligent and perceptive young woman. No one is perfect, not even Edward Cullen, but sometimes all the things I can see about Bella are her bad traits. I find myself to be a lot like Isabella Swan. I have most of her good traits, and almost all of her bad ones.
The first time I read through the books, I was not bothered with her at all. I was like, "Wow! She is just like me!" And then I started re-reading and re-reading again. You have to admit, even if you are Bella's number one fan, that she complains and often just sits there when she could be making a difference. Sometimes she is too afraid of herself and all the what-ifs that she clams up and does nothing. Perhaps if instead of letting Edward wallow in misery after her party, she could have talked to him and convinced him to stay. Or if she really looked inside of herself and admitted she loved Jake she could have saved the lot of them all the trouble and heartache. Instead, she ignores things and hopes for the best.
On the other hand, Bella is extremely caring and puts others' happiness before her own. That is what starts the whole saga off, she moves in with Charlie so Renee could travel with Phil. She lets Alice plan her wedding because she knows how happy Alice will be. She goes to Port Angeles with Jess so Charlie thinks she is not lifeless, not that he is fooled, but still.
Bella has her share of bad and good things, but sometimes, it is easy to overlook the good things about her and focus on the negative. I Bella-Bash myself, all the time. But I know her redeeming qualities, and so do I think most bashers.
(And for the record, I think Bella can be whiny and I am not jealous of her. I do not usually tend to get jealous of fictional characters, you know what I mean?)