Typeclasses: barely workable–if the implementor knows how to save the caller from paying the 'import tax'
Extension methods: too much potential for confusion
Magnet pattern: no idea what that is
Personally I feel OCaml strikes the best balance :-) But we may be arguing about an inch here rather than a mile.
I wouldn't want to have any more language features that pushed as hard as implicits do, but one somewhat-experimental feature in a language is ok, just about. I don't think Scala is a thousand-year language, but it strikes the best balance given the current state of the art.