Actor based; type safe; data-race free; copy-less message passing; easy to write fast programs; non-null types; algebraic data types; ...

Is there a specific language you would like to compare with?

A recognizable syntax is a big win, for starters. Do people still cling to the idea that it doesn't matter? How many tens of thousands of "gotchas" and "good parts" do we need to hear about from languages that have poor syntactic choices, from the viewpoint of the average programmer?

The capabilities system in particular is unique to Pony: http://tutorial.ponylang.org/capabilities/introduction/