The parity-based RAID levels still are officially not safe for production, and overall many people don't quite trust it in more complex setups due to past bugs.
It depends on your use case. BTRFS still has deficiencies in how it does quotas (significantly slows down fs if you enable quotas). BTRFS raid 5 has a write hole like traditional raid 5. And, there is a problem that sometimes occurs with individual extents when you use dedup. One of the dedup tools predicts that the issue will occur and will skip dedupe on such extents.
There were RFCs on proposals to address both the write hole and quota issues on LWN this year, with the write hole fix already having draft patches see "raid tree".
BTRFS is fine if you are not doing things that can hit those edges.
