Honestly not bad. About 7 years of use on personal machine, single volume. It simpler than ZFS and allows cheap incremental backups with send/receive.

One year ago I built a RAID56 with 5 used 2TB drives from eBay. Risky move, but it went smoothly so far. It's only for home storage and important stuff is backuped off site anyway. One Seagate drive died with lots a bad sectors. The replace command took really long even with the "-r" flag (don't read from replaced drive, in theory), so I ended up unplugging the drive and rebalancing from there.

I have high hopes for bcachefs. We have a real need for a modern FS with tiered caches. I backed the project but I don't have the skills or time to help.