I wrote a web framework (http://kemalcr.com/) and it's in production without any problem for more than 1 year on a big scale app. You can check my slides for some interesting graphs (http://www.slideshare.net/sdogruyol/kemal-rubyconfbrasil-201...)
Also be sure to check out http://crystalshards.xyz/ to discover Crystal projects(shards).
What I've felt with crystal is that I find it an immensely practical language. Maybe that stems from the compiler being written in crystal. The stdlib has so many things in that make everyday work in the language a joy. For example JSON/YAML/DB.mapping which help you map objects between JSON, YAML and the DB (they're also really fast). Including a standard, performant http stack in the stdlib is a breath of fresh air. The performance of evented io in general is really nice. The concurrency story (channels + fibers) is simple, and doesn't show itself when not required (looking at you nodejs). Most of all, the type system gets out of your way and usually only shows itself when you're making a mistake.
The question is, how easy is it to make syntax-driven tools? One thing that Ruby never did quite as well as Smalltalk was having low cost of entry for creating language parsing tools on the language itself. (At one time, there were multiple online study groups of multiple people trying to parse Ruby working for over a year. With Smalltalk, you can start hand-coding a top-down parser in the morning and be mostly done in the afternoon.)
Most of all, the type system gets out of your way and usually only shows itself when you're making a mistake.
Sounds ideal!
You can actually require the lexer and parser portions of the compiler in crystal code, and get an AST from a file relatively easily. The crystal compiler then has tools for easily walking the AST.