The decision reaffirms that the President can be held accountable for actions outside the scope of their official duties.
But notably, it does shield them from prosecution for crimes which are tangentially related to their official duties. For example, granting a presidential pardon is an official duty. Taking a bribe in exchange for that pardon would be a crime. But now the president is allowed to openly and blatantly take that bribe, because the bribe is tangential to their official duty, and they are therefore shielded from prosecution.
It does not grant blanket immunity for all actions or allow the President to act as a dictator.
Many experts disagree with the second half of your sentence, because ordering an assassination could easily be argued to be an official duty; After all, the POTUS is the commander in chief of the military. According to this ruling, ordering it illegally would be protected, because the illegality is tied to the official duty.
The C-stick and Z bumper are the two big weaknesses. If it had a proper twin-stick design instead of the C-stick nub, and actual bumpers that felt good, it would hands down be the best controller ever designed.