Minor complaint is that they have the young Dexter overact some of his more subtle mannerisms (see: the exaggerated smirk as he's walking at the end of the intro), but the casting actually was great and the actor's doing an outstanding job. I know some folks didn't like Christian Slater being cast as his dad, but I think he's doing well, young Batista and Masuka are great (yes, Masuka does the 'thing'), and young Deb is scarily good, from mannerisms to mouth.
You could chalk up the exaggeration as young, excitable Dexter vs. old, seasoned Dexter. I wouldn't be surprised if they played with the lighting or lighting saturation or whatever to make the current series "brighter" than the original to reflect Dexter's change in maturity.
The key toss at the end of the intro is a nice touch and nod to the original, even the behavioral evolution to his morning box of donuts.