Bella, as a human, has always been somewhat untouchable by most vampire's powers. Edward cannot read her mind, Jane cannot torture her, etc. Anything that has to do with manipulating or tapping into the mind does not work on Bella. As a vampire, this "power" remains, and she is untouchable. She also has great powers of restraint, and whereas most "newborns" would go crazy at the scent of a human, Bella is able to restrain by running away from the scent, and eventually easily rejecting the urge to drink blood of humans.