Novell Suse SLES11 people think so, because this enterprise distribution skips write support for ext4 in favour of btrfs.
I've tested btrfs a couple of weeks ago (with a 3.0 kernel) and I managed get 2 snapshots that could not be removed, within 20 minutes experimenting.

I don't think you should trust your most valuable assets (photo's, music tracks, development files ...) to btrfs unless you are absolutely sure you have proper backups. If you don't need btrfs for its features, don't use it for other purposes than testing.