I’m so totally stoked about this beta. I have spent a couple hours poking around, and I can say that this beta is further along than I expected. I have high hopes that this will in time replace Indesign for us (a small publisher), and it looks well on track.
Among several features that wowed right away and other "missing features" that I can work around, the one thing that stood out for me is the lack of GREP searches. In Indesign, I have a small series of GREP searches that I have saved over the past years, and I run nearly everything through them. A couple minutes on a typical file, and I have made several hundred changes. When I work on a book, the changes are in the thousands. (Note: I publish in French, and French typography relies heavily on non-breaking spaces; these GREP searches help me rapidly put them where they ought to go.)
While you're there: being able to save the searches as presets would be ideal. And as not everyone is familiar with GREP, a few pre-saved searches would help provide them immediate use: remove multiple spaces, remove trailing space, etc.