Been working with EDIFACT for 25 years (and X12, TRADACOMS, and all forms of XML). EDIFACT is, in my opinion, the most efficient way to transfer structured, repetitive data structures between different systems (mostly supply-chain or logistics). Designed to be efficient in a time when a 28.8kbps modem was fast. 12 to 15 times more compact than optimized XML. Much better than XML or JSON when you are legally bound to archive invoices for 10 years. Most mesages are around or below 5kB.
Only drawbacks:
- if you store it in a database, you can't easily query it like you would JSON.
- it only supports 1-byte encodings (EDIFACT v4 does support multi-byte encoding, but I have yet to see it used in the real world). These days, UTF-8 is everywhere.
- most end users think it's a simple text format, they code quick and dirty half-baked scripts to cobble some EDIFACT-looking garbage together and call it a day. Then they grumble when it gets rejected by a real EDIFACT parser.