I like that Ruby has a convention that is enforced about instance variables (member fields) and class variables (static member fields) i.e. @ and @@.
I introduced a similar convention recommended by somebody I met at one of the Java Users Groups when using Java in several occasions before. At one company, it was embraced. But at another company, it just sparked unnecessary discussion. It seems that experienced developers use a similar convention, one way or another. And it seems that less experienced developers oppose it for a peculiar reason.
So I like this Ruby's feature so that we can focus on writing a code that brings a value to the customer or user, instead of spending time arguing about the convention.