Reading the decision:
The court takes the logical view that the defense that a president is immune from any criminal investigation would, in essence, insulate his or her entire administration from judicial oversight.
This Court cannot endorse such a categorical and limitless assertion of presidential immunity as being countenanced by the nation’s constitutional plan, especially in light of the fundamental concerns over excessive arrogation of power that animated the Constitution’s delicate balance...”
The Court also makes a State’s rights argument against the assertion in this case (interesting if the Rethuglican’s love of State’s Rights will stand up here).
The Court decision was to dismiss the President’s suit or, in the alternative, to deny the motion for injunctive relief.
This means that an appellate court can’t just say the decision to dismiss was wrong — they would also have to address denying the injunction. This would make the overturn a harder case.
This is a long and incredibly detailed decision — great win.