No OP, but I use it sometimes because it seems to me to have a "small" core of functionality. Which made it easy for me to pickup.

It's also pretty fast.

Downside is that array's start at 1 (not suchs a big deal once you're used to it)

It’s common in the OpenStreetMap ecosystem, because an embedded scripting language is really the best way to regularise OSM’s tag soup. osm2pgsql (as used here), OSRM, and tilemaker all use it in broadly similar ways.