The disk full scenario is greatly improved. Still buggy, but it is recoverable.

Raid 5 is still consider unsafe.

Don't run postgresql on it.

So..... it's "very stable, unless you do this or that" state.

It was the default on SUSE / OpenSUSE for years. Haven't used them for a while, not sure whether it still is. No problems with basic functionality including snapshots. I believe some RAID configurations were experimental for long time.

Been using it for a year or so on my main box. Never had any kind of issue. Snapshots saved my ass a couple of times. All in all it’s been pretty boring (in a good way)

Yes. I have used it for 15 years without any problems. Just keep track of snapshots and consumed snapshot space. Besides that, works great!

Maybe. I think there's still no chance of repair when it blows up. Only FS since Reiser and early XFS that I've completely lost data to on healthy hardware.

Whichever one of my test machines is using btrfs is doing fine, though, so on a subjective level that one's been stable enough.

It's basically fine as long as you read the release notes carefully and don't do anything the release notes say not to do (e.g. RAID5, let the disk fill up). It still has some sharp edges, but they're all documented.