I think part of the issue some see is at this stage in tech development, things should be faster. Not saying I agree with this, but to be honest, that's how we have seen development happening, faster and faster. I think I heard about publisher 2 years or more ago, looked promising from discussions, but if you cannot even open an indesign file to test it or test export for digital content like ebooks, it is tough to say it looks promising. I believe those features should have been there for the beta, they make sense in that people will be comparing that way. How does this handle this indesign file I have, what breaks, what needs to change, etc. For ebooks, to not have even say just reflowable epub export seems odd not too mention they said they aren't even sure when that feature will be added or if it will, you'd think they have a roadmap to have an idea on features.
Maybe it has potential or maybe it doesn't, but if key components aren't there for people to test, then they are less likely to say great things about something they cannot even test, it's not as relevant for them then.