I went down the rabbit hole of trying to find the best binary JSON-ish format a couple of years ago, it's very interesting to compare their different design choices. Having read the specification, this looks to be a fresh and minimalist take on a binary format, which is great.

In general, it seems CBOR won the standardisation and support battle while also being one of the more complex and ambiguous (in terms of the number of ways to encode something) formats. I think MessagePack is nicer, though I still wish UBJSON caught on.