It's always a method. Ruby doesn't expose instance variables unless you define accessor methods for them.
Unlike with other languages, there is no ambiguity here.
In python, you don't know when you dir() an object whether your dealing with a property or method. In Ruby, you are guaranteed it's always a method. A perk is that you don't need parens.
And I think I’m in the minority here, but I prefer the cleanliness of optional punctuation.
That feature also allows for fluent DSLs (which seem to be falling out of favor for various reasons), but is one of the reasons I still love Ruby.
To look at the other side, I hate having to constantly add semicolons and parens in other languages. Makes my poor fingers hurt even more than they usually do.