IMO, it has the best ergonomics among scripting languages for embedding into native applications. I'm using it as a serialization format for a game, with the JimTcl interpreter. It's easy to create fluent hierarchical structures that straddle the line between code and data:

  object "player" {
    health 100
    ammo 10
  }

https://github.com/msteveb/jimtcl