Most obviously, Miers is a Christian conservative. She also has "been there, done that" in the real world and thus would bring a new and much needed perspective to the court. She has also vetted this administration's nominations to the various courts so she knows the goal and the criteria and the players.
Very significantly, people who have known her for decades, endorse her. This President who rarely makes a mistake in sizing up a member of his team that he personally chooses, trusts her.
I know a little of Coulter's background. I believe she has devolved into a caricature rightwing MSM. Sadly she is not alone in displaying the same kneejerk reactions that we have come to despise among the left.