I have not used it in production yet, but it's been great for one-off scripts and side projects. Setting up a TypeScript Node environment with ts-node, ts-jest, ESM support, top level await, etc. is more annoying than it should be. More recent Node releases have alleviated some of this pain, but not as trivial as running bun init.
I've enjoyed using the bun shell [1] API.
[1] https://bun.sh/blog/the-bun-shell