Miers – a non-partisan bad choice
Charles Krauthammer wrote, "If Harriet Miers were not a crony of the President of the United States, her nomination to the Supreme Court would be a joke, as it would have occurred to no one else to nominate her."
George Will spoke against her as well, saying, "There is no reason to believe that Miers' nomination resulted from the president's careful consultation with people capable of such judgments. If 100 such people had been asked to list 100 individuals who have given evidence of the reflectiveness and excellence requisite in a justice, Miers' name probably would not have appeared in any of the 10,000 places on those lists."
A Supreme Court Justice needs a thorough understanding of constitutional law and a wide range of legal experience. There's no requirement that a nominee for the Court must have served as a judge at a lower level, but a person who lacks that experience should have an impressive legal mind and be able to demonstarte their superior ability over any other possible candidate.
Miers can meet neither standard. Based on the small amount of public records regarding her accomplishments and opinions, she may well be the least capable person ever nominated to the Court. But that's probably an appropriate choice, coming from the least capable President in American history.