Do yourself a favour and listen to her discussing Iraq, here (or read the story and transcript, here, but the audio gives you a better sense of her command of the issues). It's from an interview series the NY Times is doing with the candidates on Iraq.
Listen to the substance, knowledge and sensible positions. Then imagine George W. Bush sitting down to do the same.
She gets a ton of flak for her personality, history, etc., but when you sit and listen to her, you think, you know what...she makes a lot of sense. It may just be as simple as that.