I read the book and saw the movie. I think it was a fairly accurate portrayal of her based on what facts we do know. We have no shortage of direct quotes from her which paint a picture of her personality. She appears to be highly narcissistic, vindictive, petty, paranoid and not very knowledgeable or articulate.
She is a Christian evangelical, believing that God is directing her personally. Her loyalties seem to be very changeable. She is a grifter at heart - looking out for her bottom-line regardless of principles. We have yet to discover what she won't do for a buck.
That represents my view, but there are 10-15% of the American public who think she's swell.