My team has been using it in prod for about a year now. There were some minor bugs in the runtime's implementation of buffers in 1.22 (?), but that was about the only issue we ran into.
The nice things:
1. It's fast.
2. The standard library is great. (This may be less of an advantage over Deno.)
3. There's a ton of momentum behind it.
4. It's closer to Node.js than Deno is, at least last I tried. There were a bunch of little Node <> Deno papercuts. For example, Deno wanted .ts extensions on all imports.
5. I don't have to think about JSR.
The warts:
1. The package manager has some issues that make it hard for us to use. I've forgotten why now, but this in particular bit us in the ass: https://github.com/oven-sh/bun/issues/6608. We use PNPM and are very happy with it, even if it's not as fast as Bun's package manager.
Overall, Deno felt to me like they were building a parallel ecosystem that I don't have a ton of conviction in, while Bun feels focused on meeting me where I am.