For me a HUGE feature is:

"Mirah code has no runtime dependency other than libraries accessed directly from Mirah code."

Wow - Charles has done an amazing job sticking true to that. In fact so much I thought it was a core aim.

I love scala, clojure - but there is significant runtime libraries to include. for most people this isn't an issue (and it isnt' for me most of the time) but Mirah doing what it does without runtime deps, is a refreshing alternative.