I don't think btrfs and its fsck are really stable... Can someone prove me wrong?
No arguments there. From time to time I think to myself "well some time has passed, maybe it's actually usable now", and then I try to use it and always get lots of kernel backtraces in my dmesg. The root seems to be common: I try it on small partitions, and btrfs still chokes when the partition is almost full. But c'mon, I really don't care. It's just not usable, and I'd never recommend it.
Btrfs is considered stable by Oracle (for what that's worth) and Suse. It's also now considered stable by me, which is the most important thing . All of my testing is with Kernel 3.4, and latest btrfs-progs. Don't use it on an earlier kernel.
I've been testing it theroughly without trouble. Online adding and deleting devices from arrays works wonderfully. Scrubbing works well, much the same as ZFS scrubbing.
The most important thing is that Btrfs seems to be extremely resiliant against corruption, and the so called "self healing" has worked well. Having checksums for everything is really the way to go.
Btrfs has been great, so I don't think the negative comments are still deserved. I recommend everyone try it for themselves in the lab. I DON'T recommend you try it if your a desktop user with a single hard drive. It's probably not meant for you anyhow.