It's "just syntax" in that it over little more than a different name from the keyword 'package' - the only difference is that it comes with a trailing scope.

It does more than that. The block executes at BEGIN time, and you can optionally inherit from multiple parents with class Baz is Bar is Foo { ... }.

That's not a complete revision of Perl 5's object system, but it is a start. Besides that, it's exactly the syntax of Perl 6 -- and I believe it's more descriptive and easier to understand than messing with @ISA or base or parent.