I don't know anything about Harriet Miers other than the little that's been in the press. I kind of like that she has not been a judge but has a lot of litigation experience. The liberals and Democrats, though, are howling that she has no experience as a judge.
There are some darlings of the left who have also sat on the bench without previous judicial experience.
William O. Douglas was appointed to the court in 1939 by Franklin Roosevelt. He had been serving as a member of the Securities and Exchange Commission. He was considered for the Democratic VP position in both 1944 and 1948. He had no prior experience.
Earl Warren was serving as Governor of California when he was picked for the bench by Dwight Eisenhower. He had absolutely no prior judicial experience.
What do you complainers think of that? And then -
Byron "Whizzer" White also served on the Warren court. He never served on the bench either - he helped run the Kennedy campaign in Colorodo before being chosen by the same Kennedy for the Court.
Robert Jackson never earned a law degree. He served at Solicitor General and Attorney General under Roosevelt, and was appointed to the bench by FDR. He took a leave of absence to serve as the chief prosecutor at the Neuremburg war crimes trials.