There is just a high level of a professionalism around the whole project. Who is sponsoring all of this? Do they all work for Oracle?
I strongly suggest watching some of their talks from JVMLS (JVM Language Summit), especially the ones from Brian Goetz and Mark Reinhold.
https://www.youtube.com/playlist?list=PLX8CzqL3ArzUOgZpIX6Gs...