D&D 5E Common rules mistakes

[aramis erak]

Another thing that should be noted is how grappling is no longer a wizard shutdown technique. I really like how they stopped all the rock-paper-scissors crap when it comes to spellcasters.

Yeah. Now, to stop them spellcasting you either disarm their focus or actually grapple and pin. Or, to end concentration, actually hurt them.

One more thing is the rebuilt saving throw system. No particular save is a guaranteed success and no save is a guaranteed fail.

That actually is nothing new; there was wording to that effect in most editions.
That the range of DCs in practical use means that the automake on 20 and the autofail on 1 aren't all that commonly the only way to succeed/fail. Which I like.

 

[miniaturehoarder]

Yeah. Now, to stop them spellcasting you either disarm their focus or actually grapple and pin.

Disarm is an option the DM chooses whether or not to add. Also there is no "pin" when grappling to stop casting, closest to that is the Restrained condition those with the grapple-y feat can apply.