I haven't read the text of the opinion yet, so I will not go overboard, but it seems to me that under this ruling Nixon wouldn't have been required to turn over the Watergate tapes.
This case and
United States v. Nixon (1974) are easily distinguishable. In
Nixon, the subpoenas were issued pursuant to a criminal investigation, over which the judiciary had unquestioned authority. Nixon's claim that he was not required to comply was based on a specific theory of "executive privilege" rather than a blanket refusal to cooperate. Also, the dispute wasn't between Congress and the president, but between an executive branch prosecutor and the president.
If you would like to read the court of appeals opinion,
it's available here.
By the way, I am sure that since this was a 2-1 decision before a three judge panel, Congress will file a motion for rehearing before all the judges of the D.C. Circuit, and that the loser will appeal it to the Supreme Court. I don't think we have heard the last of this.
Correct on both counts: it was a 2-1 decision and there was even some disagreement (not relevant here) between the two judges in the majority. The next step, should the House of Representatives decide to proceed with the litigation, would be an en banc hearing before the court of appeals. And, of course, the losing party at that level could petition the U.S. Supreme Court to consider the case.