The opinion concludes that the 14th Amendment does incorporate the Second Amendment right recognized in Heller to keep and bear arms in self defense
Stevens dissents for himself. Breyer dissents, joined by Ginsburg and Sotomayor.
The majority seems divided, presumably on the precise standard
The majority Justices do not support all parts of the Alito opinion, but all five agree that the 2d Amendment applies to state and local government.
Alito, in the part of the opinion joined by three Justices, concludes that the 2d Amendment is incorporated through the Due Process Clause.
Thomas thinks the Amendment is incorporated, but not under Due Process. He appears to base incorporation on Privileges or Immunities.
The difference between the majority and Justice Thomas doesn't affect the fact that the Second Amendment now applies to state and local regulation.
It should be noted that, in the guns case, the Court says explicitly in Alito's opinion that it would not reconsider the Slaughterhouse cases, which almost completely deprive the Privileges or Immunities Clause of any constitutional meaning.
The opinion leaves the fate of the Chicago gun ordinance in the hands of the 7th Circuit on remand.
The scope of the Chicago gun ordinance in question in McDonald is very similar to that of the DC gun law struck down in DC v. Heller in 2008. Therefore its fate is probably already determined by applying Heller's reasoning to it.
Let the hand-wringing commence!