I operate an app that orchestrates code running on a bunch of Sprites. A few months ago it was an exceptionally buggy service, frequently just fully broken or losing data (had to get support involved to recover one that got into a fully broken state), but from what I've seen at least they've become much more reliable in the past two months or so.

I evaluated Fly.io itself several years ago and found it unacceptably buggy as well for any real use case at the time, but I kept an eye on it and today I operate a few production workloads on it that are very stable and reliable—I figured the same would be true for Sprites and it seems to be taking shape that way.