BTRFS does not seem to recover well from media errors. I've had plenty of those, and always been able to recover at least partial data (minus the bad media) with other FS's.
Some testing seems to indicate even ext4 is more reliable in the face of hard power cycles.
I was using BTRFS on my workstation and all of a sudden some garbage got written to the extent-tree, and it was toast. Never using BTRFS again. I had backups and was able to recover 99.99%, but the recuse tools were garbage. I finally killed it after it had spent a month, from July 4 until August 4, doing apparently nothing. And this was this year. This was a normal desktop configuration, single drive. I wasn't using any of the real features of the FS other than COW.
To be fair, I think I've lost more data on btrfs.
My experience about a year ago was the opposite, btrfs held up really well on a failing drive and I managed to copy the filesystem with 'btrfs send' without suffering any data loss or corruption as far as I've been able to tell. I also had a btrfs filesystem on an external drive with a lose USB plug that caused it to disconnect once in a while, and didn't have any corruptions or loss on that one either.