I like where they're coming from. But, after a couple minutes of looking, I have some concerns.
1. the signature based authentication algorithm is susceptible to being replayed.
2. there's no real way to negotiate protocols.
3. websockets as a *lower overhead* transport 😕 ???? What?
That said, there is a lot to like:
simple models
required fields
instance metadata
delegation (even if it's not adequate for the purposes I would want)
real extension mechanism