- tooling: there is a VS Code plugin for Crystal (https://marketplace.visualstudio.com/items?itemName=crystal-...). There is also syntax highlighting for most popular editors, if you prefer a text-editor to a fully-loaded IDE.

- no multi threading: Crystal has lightweight green threads for lightweight concurrency. However, Crystal does have experimental native multi-threading guarded by a compiler flag. The ultimate goal is to have multiple native threads each running multiple green threads for maximum concurrency. Currently, with just green threads, Crystal is competitive with Go or Rust wrt throughput. You can checkout benchmarks on crystal-lang.org or search Google for "Go vs Crystal benchmark" blog posts.

- no real support: Manas Tech is the corporate sponsor for Crystal (https://manas.tech/projects/crystal/) and employs many of the core developers; the project also accepts donations on Open Collective. There is a crystal-lang IRC channel, Gitter, Discord, Discourse forum, sub-reddit, and even a "Matrix" channel where developers frequently ask and answer questions.

- still immature: a 1.0.0 version is a significant milestone for any project. Companies are already running Crystal in production, which was discussed during the Raw Crystal 2020 virtual-conference (videos on YouTube).

- API breakage: Crystal 1.0.0 was released to stabilize the API (SemVer)