Charles Krauthammer thinks that on constitutional matters, Roberts is a tabula rasa. Bill Kristol is persuaded that Roberts is a conservative on constitutional matters. Worth reading, with a great story by a former law clerk (a liberal) who not only maintains that Roberts is conservative, but also insightfully asserts that given his congenial nature he is likely to have a huge impact on the Court, and "he could ultimately be a progressiveâ€™s worst case scenario." Also see Powerline.
And here is
Michael Baroneâ€™s take on Roberts: "Justice Roberts will do much to redefine what is the mainstream in American constitutional law."
UPDATE: Anita Hill, the world famous, extremely bright, widely published professor of law--although your memories of her may differ--has an opinion (or two or three) about Roberts. I havenâ€™t heard her name mentioned in years; now I know why.