I've been using it and it's been fun for learning rust. I've only done DNS and web server modules so far, but it has helped a lot in giving me goals that are achievable

(disclaimer: I work at CodeCrafters)

CodeCrafters is a bit light on Elixir support at the moment (only 2/8 challenges support it so far). We're planning on expanding Elixir support soon.

Currently, we're a great fit for Rust / Python / Go - we support a variety of challenges for those, and there's lots of example code from other users to review and learn from.