It seems much more directly comparable with CBOR/JSON as they mention it a lot https://amzn.github.io/ion-docs/guides/why.html#dual-format-... . I use CBOR quite a bit. It sounds like it doesn't really offer too much different in the binary form other than in the textual form it maintains better types than JSON and the textual version matches the binary version (where JSON / CBOR are mismatched in terms of types). So, seems nicer as a cohesive textual/binary format. I'd be interested in seeing how well packed the data is in Ion vs CBOR.