I agree. Almost all class systems now are rehashes of things that are useful and were once very exciting, but now you've seen them in tens of languages.

When you encounter yet another one, learning it is usually a matter of seeing which set of semantics it provides (probably all of which you've seen before), and the exact way they do it.

Though one nice feature they included with Racket's `class` library, which was unusual (but not new) at the time, is mixins: https://docs.racket-lang.org/guide/classes.html#%28part._.Mi...