I didn't really care for Ginny (although I wasn't fond of her due to the opinions of some Harry/Ginny fans) until she became more independent in OotP. I really liked here there.
I tended to say that the only one to be able to make me believe in Harry/Ginny was JK Rowling - and she just ruined it and made it completely unbelievable to me. HBP to me is a badly written fanfiction.