Much of A12 is, as you pointed out, about implementation. To us mere mortals, it's the kind of thing that's interesting to know, but really I didn't try too hard to understand the dispatching details. All I need to know is that I can write methods with the same name and different signatures and it will work. And I barely more than skimmed any paragraph that mentioned an ALLCAPS sub. Things like BUILD, BUILDALL, AUTOMETH, etc., are just kind of vague things that do stuff I probably won't need to change in the near future, if ever.
Roles are more for the Class Writer than the User. They're just little bits of abstracted behavior that you can throw into classes that need the behavior. They're useful to get away from writing lots of abstract classes that just contain behavior and then doing multiple inheritance all over.
As a Class User, you pretty much just do what you do now. As long as the Writer has done their job correctly, you just do:
In fact, even deriving from a class that uses Roles doesn't require knowing about them. To your derived class, any methods implemented as Roles in the base class look like any other derived method to your class.use SomeClass; my $obj = SomeClass.new; $obj.something; # etc.
I'm not too sure about Traits, myself, so I'll refrain from commenting on them at all. A good example involving what Traits are and how to use them would be my request for E12.