9-0 on ANYTHING is pretty astonishing!
The decision was 9-0 that these particular appointments were invalid, but the grounds of the decision were WAY narrower than the lower court.
The D.C. Circuit had held that the recess appointment power can only be used during the recess between one Congress and another (not during recesses in the middle of one Congress), and only if the vacancy happens during that recess. That decision would have, in effect, ended the recess appointment power entirely. (It also meant that all of the recess appointments made during the past 100 years were unconstitutional.)
Today's decision just says that the President can't make a recess appointment at a time when the Senate says it's in session. It strikes down these appointments, but leaves Obama and future presidents much more room for making recess appointments than the lower court would have.