Production-worthiness depends on your needs. The free edition is perfectly good for most people, however there are several features and modules that are only available in the Enterprise Edition. Notably, some of the disaster recovery, scaleout, and multifactor authentication features cost extra.

ref: https://www.hashicorp.com/products/vault/pricing

I think the problem was that auto-unseal wasn't free (it is now, so kudos to HashiCorp for listening).