I think it's great. If you're a fan of Ruby it's hard not to like. I'd say it competes with go in many respects. If Ruby is your daily driver crystal is perfect for cases where you need more performance or where non blocking io would be a good fit.
We are using Crystal for our mail flow monitoring tool at mailflowmonitoring.com - create a free account and you can check it in action. It was a delight to deal with. We also created a Crystal email parser - https://github.com/amrood-labs/mail.cr
Or where you want to deploy some small tools without worrying about setting up rbenv and dealing with bundler in your config management.
Thanks, I have wanted to try it. I will find some small project to use Crystal for.