The reversal was expected and is not the first time an appointee has been reversed by the court he was about to join.
Indeed, two of Chief Justice Warren Burger's opinions for the D.C. Circuit Court of Appeals were reversed in 1969, the year he joined the court. One was Watts v. United States, in which the defendant had been convicted for threatening the life of the president.
By a 5-4 vote, the Supreme Court reversed, holding that Watts' supposed threats were really nothing but hyperbole. The decision came down one month before President Nixon nominated Burger. More significantly, after Burger had been confirmed, the Court reversed him again, this time in a major case -- Powell v. McCormack.
I also think this piece in Forbes is an interesting one on why Republicans should not oppose Sotomayer.