Crystal is great! It's still being under development but there's not many breaking changes after 0.20.0+ and it's getting smoother day by day.
Parallelism and Windows support are on the way. BTW feel free to join the superb friendly community on Gitter <a href="https://gitter.im/crystal-lang/crystal" rel="nofollow">https://gitter.im/crystal-lang/crystal</a> :)<p>[Shameless plug] I'm the author of Kemal(<a href="http://kemalcr.com/" rel="nofollow">http://kemalcr.com/</a>): Fast, Effective, Simple web framework.[/Shameless plug]