My most favorite features of Crystal include format, spec, docs, dependencies management.<p>Macro is more magic than Ruby, it's a bit inconsistent to me for now, but it could be improved in documentation.<p>Working with Generics is a bit "trial, guess and error", due to lack of documentation again.<p>ORM is a bit lacking.<p>Other than that, it's more than enough to deliver production-ready codebase in a pleasant, simple and clean way.